WEBVTT 00:00:00.620 --> 00:00:01.460 Hi, everyone. NOTE CONF {"raw":[98,100]} 00:00:01.760 --> 00:00:02.930 My name is Simil. NOTE CONF {"raw":[100,100,100,42]} 00:00:02.960 --> 00:00:05.600 And in this short video, I will walk you through NOTE CONF {"raw":[100,100,100,100,100,100,97,100,100,100]} 00:00:05.930 --> 00:00:11.390 an example of the importance of geometric series in the NOTE CONF {"raw":[100,100,100,100,100,100,100,84,100,100]} 00:00:11.390 --> 00:00:14.960 context of economics, and in particular in the context of NOTE CONF {"raw":[100,100,99,99,100,100,100,100,100,100]} 00:00:15.140 --> 00:00:16.970 investment decisions. NOTE CONF {"raw":[100,100]} 00:00:18.080 --> 00:00:24.080 So an investment projects typically involves incurring a large cost NOTE CONF {"raw":[100,72,100,58,100,75,100,95,96,91]} 00:00:24.260 --> 00:00:29.120 today in anticipation of a certain stream of payoffs in NOTE CONF {"raw":[100,100,100,100,99,100,60,100,86,100]} 00:00:29.120 --> 00:00:29.660 the future. NOTE CONF {"raw":[100,100]} 00:00:30.200 --> 00:00:33.140 For example, an investment project as well, where a bomb NOTE CONF {"raw":[100,100,78,100,99,57,82,100,100,98]} 00:00:33.140 --> 00:00:36.110 went build the factory today in order to produce and NOTE CONF {"raw":[51,97,67,100,100,100,100,100,100,100]} 00:00:36.110 --> 00:00:39.680 sell out for a particular amount of time, for example, NOTE CONF {"raw":[65,69,97,100,100,100,100,100,100,100]} 00:00:39.680 --> 00:00:43.370 30 years, so long as the factory is in operation. NOTE CONF {"raw":[89,100,100,100,100,100,100,100,100,100]} 00:00:44.820 --> 00:00:47.560 A firm should implement an investment project. NOTE CONF {"raw":[91,89,100,100,99,100,95]} 00:00:48.090 --> 00:00:52.050 All if the payoffs from the project exceed the cost. NOTE CONF {"raw":[60,50,100,87,100,100,100,100,100,78]} 00:00:52.500 --> 00:00:56.160 However, one of the issues that occurs in the context NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:00:56.160 --> 00:00:59.700 of investment projects is that that the costs and payoffs, NOTE CONF {"raw":[100,100,93,100,73,100,100,100,100,98]} 00:00:59.700 --> 00:01:02.340 in fact, the crew at different points in time. NOTE CONF {"raw":[74,74,100,99,100,100,100,100,100]} 00:01:03.090 --> 00:01:06.750 And this creates a difficulty because of what is known NOTE CONF {"raw":[100,100,100,100,100,100,100,99,99,100]} 00:01:06.750 --> 00:01:08.910 as the time value of money. NOTE CONF {"raw":[100,100,100,100,100,100]} 00:01:10.440 --> 00:01:13.770 The time value of money is the principal loosely speaking, NOTE CONF {"raw":[100,100,100,99,100,100,100,68,80,100]} 00:01:13.770 --> 00:01:19.020 that because if interest rates went down today is not NOTE CONF {"raw":[65,100,54,100,100,86,77,100,76,100]} 00:01:19.020 --> 00:01:22.230 the same in terms of value as £1. NOTE CONF {"raw":[100,100,100,100,100,100,100,55]} 00:01:22.320 --> 00:01:26.940 One year from now, for example, if the interest rates NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,76]} 00:01:27.330 --> 00:01:29.370 are equal to five percent. NOTE CONF {"raw":[100,100,100,100,100]} 00:01:30.150 --> 00:01:33.840 And if I have one thing today, then through my NOTE CONF {"raw":[100,100,100,99,97,43,100,99,97,100]} 00:01:33.840 --> 00:01:37.980 access to a bank which base interest rates, I can't NOTE CONF {"raw":[100,100,100,100,100,48,100,100,100,56]} 00:01:37.980 --> 00:01:42.390 convert this one pound today into one point five pounds NOTE CONF {"raw":[100,100,64,64,100,100,99,99,100,99]} 00:01:42.630 --> 00:01:43.830 one year from now. NOTE CONF {"raw":[100,100,100,100]} 00:01:44.840 --> 00:01:47.360 By depositing this one pound in a bank. NOTE CONF {"raw":[100,99,100,93,93,100,51,100]} 00:01:48.420 --> 00:01:51.210 We say in this context that the future value of NOTE CONF {"raw":[100,100,100,100,100,82,100,100,100,100]} 00:01:51.210 --> 00:01:54.810 one pound today in one year is exactly one pound NOTE CONF {"raw":[84,50,100,100,99,98,99,100,100,100]} 00:01:54.810 --> 00:01:57.000 multiplied by one, plus the interest rate. NOTE CONF {"raw":[97,100,100,100,100,100,90]} 00:01:57.900 --> 00:02:01.060 But similarly, if I actually hold my money in the NOTE CONF {"raw":[100,100,100,100,100,97,100,100,100,99]} 00:02:01.060 --> 00:02:05.400 deposit for two years, I can convert my one pump NOTE CONF {"raw":[48,99,100,100,100,100,100,98,100,88]} 00:02:05.400 --> 00:02:08.070 even more money to pyrates into the future. NOTE CONF {"raw":[100,100,100,98,89,100,100,100]} 00:02:08.070 --> 00:02:11.370 And we say equivalently that the future value of £1 NOTE CONF {"raw":[100,100,96,100,100,100,100,100,100,82]} 00:02:11.370 --> 00:02:15.240 today in two years is this one bond multiplied by NOTE CONF {"raw":[100,100,100,100,100,100,88,30,100,100]} 00:02:15.420 --> 00:02:19.170 one, plus the interest rate squared and so forth. NOTE CONF {"raw":[100,100,99,100,100,73,100,100,86]} 00:02:20.920 --> 00:02:25.570 Now, this arguments underlying the time value of money also NOTE CONF {"raw":[100,56,49,91,100,100,100,99,100,100]} 00:02:25.570 --> 00:02:26.890 works backwards. NOTE CONF {"raw":[100,100]} 00:02:27.520 --> 00:02:30.570 For example, if the interest rate is five percent and NOTE CONF {"raw":[100,100,99,100,100,99,100,100,100,99]} 00:02:30.580 --> 00:02:34.510 I am to receive £1 one year into the future, NOTE CONF {"raw":[92,92,100,100,58,100,100,100,100,100]} 00:02:35.170 --> 00:02:40.720 then this is very much like receiving one divided by NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:02:40.720 --> 00:02:46.390 one point five or approximately ninety five pence today, because NOTE CONF {"raw":[99,98,78,80,100,75,75,61,100,100]} 00:02:46.390 --> 00:02:49.450 if I had ninety five pence today, I can deposit NOTE CONF {"raw":[99,100,43,86,86,97,100,100,95,100]} 00:02:49.450 --> 00:02:52.420 them in a bank at the interest rate, the five NOTE CONF {"raw":[100,100,100,100,100,100,100,100,64,99]} 00:02:52.420 --> 00:02:55.090 percent, and convert it into account. NOTE CONF {"raw":[99,100,100,98,100,83]} 00:02:55.780 --> 00:02:56.800 One year from now. NOTE CONF {"raw":[100,100,100,100]} 00:02:57.690 --> 00:03:00.660 In this context, we say that the present value of NOTE CONF {"raw":[100,100,100,100,100,100,100,97,100,100]} 00:03:00.660 --> 00:03:05.610 £1 received one year from now is Wangan divided by NOTE CONF {"raw":[91,100,100,100,100,100,100,76,99,100]} 00:03:05.700 --> 00:03:06.060 one. NOTE CONF {"raw":[100]} 00:03:06.060 --> 00:03:09.180 Plus, the interest rate, the present value of £1 received NOTE CONF {"raw":[98,100,100,92,100,100,100,98,92,97]} 00:03:09.180 --> 00:03:12.510 two years from now is £1 divided by one plus NOTE CONF {"raw":[86,100,100,100,91,93,100,100,100,100]} 00:03:12.810 --> 00:03:14.130 R squared. NOTE CONF {"raw":[49,48]} 00:03:14.610 --> 00:03:15.390 And so far. NOTE CONF {"raw":[100,51,49]} 00:03:17.260 --> 00:03:21.100 When a firm decides whether to implement an investment project NOTE CONF {"raw":[100,100,100,98,100,99,100,100,100,100]} 00:03:21.340 --> 00:03:25.270 or not, it should compare all the payoffs and costs NOTE CONF {"raw":[100,100,100,98,99,93,100,80,100,100]} 00:03:25.270 --> 00:03:27.730 from the project in present value terms. NOTE CONF {"raw":[100,100,88,69,94,100,100]} 00:03:29.080 --> 00:03:32.050 And one January to do this is to use the NOTE CONF {"raw":[100,100,41,98,97,99,100,100,100,99]} 00:03:32.050 --> 00:03:35.170 what's known as the net present value calculation. NOTE CONF {"raw":[100,100,100,98,100,100,100,96]} 00:03:35.170 --> 00:03:39.820 So the net present value of a project is the NOTE CONF {"raw":[100,100,100,100,100,60,79,100,100,100]} 00:03:39.820 --> 00:03:43.270 sum of for the present value of all payoffs from NOTE CONF {"raw":[99,39,60,100,100,100,87,83,95,100]} 00:03:43.270 --> 00:03:47.770 the project, minus the present value of all costs from NOTE CONF {"raw":[100,100,100,100,100,81,97,66,100,100]} 00:03:47.770 --> 00:03:48.460 the project. NOTE CONF {"raw":[100,99]} 00:03:48.910 --> 00:03:51.670 If the net present value of the project exceeds zero, NOTE CONF {"raw":[98,99,100,100,100,97,63,100,82,100]} 00:03:51.670 --> 00:03:53.890 then the project is worthwhile implementing. NOTE CONF {"raw":[100,100,100,99,100,68]} 00:03:54.190 --> 00:03:56.770 But if it is below zero, then the project should NOTE CONF {"raw":[100,100,100,100,100,100,100,100,89,100]} 00:03:56.770 --> 00:04:00.400 not be implemented and the firm is better off depositing NOTE CONF {"raw":[100,100,100,84,100,78,100,100,100,100]} 00:04:01.030 --> 00:04:03.460 their money in a bank account instead. NOTE CONF {"raw":[100,100,100,100,100,100,99]} 00:04:05.110 --> 00:04:08.890 Let's consider a numerical example which will clarify the importance NOTE CONF {"raw":[90,100,99,99,100,100,100,100,100,100]} 00:04:08.890 --> 00:04:13.210 of geometric series in this discussion, so suppose that there NOTE CONF {"raw":[100,100,84,100,100,100,100,100,100,100]} 00:04:13.210 --> 00:04:16.269 is a project, a form Kesem project, and the cost NOTE CONF {"raw":[100,94,100,88,46,60,100,69,100,82]} 00:04:16.660 --> 00:04:20.890 of implementing this project is one point five million pounds, NOTE CONF {"raw":[100,100,100,100,97,100,100,100,100,100]} 00:04:20.980 --> 00:04:23.980 which has to be incurred today, for example, in order NOTE CONF {"raw":[100,99,100,100,98,99,100,100,100,100]} 00:04:23.980 --> 00:04:24.880 to build the factory. NOTE CONF {"raw":[100,100,98,100]} 00:04:26.030 --> 00:04:30.680 If implemented, the project will pay off one hundred thousand NOTE CONF {"raw":[100,100,100,99,100,100,100,100,100,100]} 00:04:30.680 --> 00:04:35.660 pounds each year for 20 years with the first payoff. NOTE CONF {"raw":[100,100,100,100,71,100,100,100,99,96]} 00:04:35.750 --> 00:04:38.690 A great one year into the future after the cost NOTE CONF {"raw":[100,99,100,100,100,100,100,100,100,93]} 00:04:38.690 --> 00:04:42.600 is incurred, perhaps because it takes one year to build NOTE CONF {"raw":[93,92,100,100,100,100,100,100,100,94]} 00:04:42.600 --> 00:04:45.910 the factory and then you start producing and selling out, NOTE CONF {"raw":[80,100,100,100,100,100,100,97,100,87]} 00:04:45.920 --> 00:04:47.810 but only from one year into the future. NOTE CONF {"raw":[36,80,100,100,100,100,100,100]} 00:04:47.840 --> 00:04:51.950 So an interesting question is, is this project worthwhile? NOTE CONF {"raw":[100,100,100,100,99,100,100,100,100]} 00:04:51.980 --> 00:04:53.960 Should it be implemented by the four? NOTE CONF {"raw":[100,100,100,100,100,100,30]} 00:04:55.150 --> 00:04:58.930 Well, in order to answer this question, we should calculate NOTE CONF {"raw":[100,100,100,100,100,100,100,100,99,100]} 00:04:58.930 --> 00:05:01.060 the net present value of the project. NOTE CONF {"raw":[100,94,100,100,99,73,97]} 00:05:01.750 --> 00:05:06.130 Well, given that the interest rate is denoted by the NOTE CONF {"raw":[99,100,100,100,100,100,100,100,94,94]} 00:05:06.160 --> 00:05:09.280 net present value of this project in thousands of pounds, NOTE CONF {"raw":[100,100,100,100,100,100,80,100,100,86]} 00:05:09.280 --> 00:05:14.890 this minus fifteen hundred thousand pounds, this is the negative NOTE CONF {"raw":[42,100,100,100,100,100,100,100,100,92]} 00:05:15.010 --> 00:05:16.510 of the cost incurred today. NOTE CONF {"raw":[100,100,70,100,100]} 00:05:16.960 --> 00:05:19.690 And then one year into the future, where receive pay NOTE CONF {"raw":[100,100,100,91,100,100,100,64,66,63]} 00:05:19.690 --> 00:05:20.860 of one hundred thousand. NOTE CONF {"raw":[81,94,94,95]} 00:05:20.860 --> 00:05:22.720 But because it's one year into the future, we have NOTE CONF {"raw":[99,100,99,100,100,100,100,100,100,100]} 00:05:22.720 --> 00:05:24.400 to divide it by one. NOTE CONF {"raw":[97,97,73,100,100]} 00:05:24.400 --> 00:05:27.780 Plus, sorry to convert the present values that three years NOTE CONF {"raw":[97,27,99,100,99,99,98,100,76,76]} 00:05:27.820 --> 00:05:30.940 into the future, we receive another 100000. NOTE CONF {"raw":[100,100,100,100,83,100,72]} 00:05:31.210 --> 00:05:34.240 But in order to discount them in present value terms, NOTE CONF {"raw":[100,98,98,99,100,100,100,100,100,100]} 00:05:34.240 --> 00:05:37.210 we divide by one plus our square and so forth, NOTE CONF {"raw":[100,100,100,100,100,97,97,100,100,99]} 00:05:37.660 --> 00:05:41.470 all the way until twenty one years into the future. NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:05:41.470 --> 00:05:45.550 We receive 20 years into the future, receive £100, and NOTE CONF {"raw":[97,100,68,100,96,98,100,84,95,100]} 00:05:45.550 --> 00:05:46.870 we discounted by one. NOTE CONF {"raw":[88,99,100,100]} 00:05:46.870 --> 00:05:48.870 Plus are the power of twenty. NOTE CONF {"raw":[99,63,100,100,76,37]} 00:05:50.370 --> 00:05:54.360 Now, the usefulness of geometric series in the context of NOTE CONF {"raw":[100,100,100,100,99,98,100,100,100,100]} 00:05:54.360 --> 00:06:01.140 this calculation comes from recognising that the payoffs shown on NOTE CONF {"raw":[98,98,100,100,97,100,100,61,74,100]} 00:06:01.140 --> 00:06:07.770 the slides, in fact, form a geometric series with first NOTE CONF {"raw":[100,96,100,100,99,96,100,100,100,97]} 00:06:07.770 --> 00:06:08.190 element. NOTE CONF {"raw":[74]} 00:06:08.460 --> 00:06:12.540 Why can't rates over one plus are a common ratio NOTE CONF {"raw":[57,51,52,100,99,74,96,98,100,100]} 00:06:13.050 --> 00:06:13.800 of the elements? NOTE CONF {"raw":[100,100,93]} 00:06:13.950 --> 00:06:17.400 One over one, plus the interest rate and with 20 NOTE CONF {"raw":[100,100,100,100,100,100,96,99,99,87]} 00:06:17.400 --> 00:06:17.970 terms. NOTE CONF {"raw":[54]} 00:06:19.220 --> 00:06:23.330 If we know the formula for the sum of the NOTE CONF {"raw":[100,100,100,100,93,92,100,93,100,100]} 00:06:23.330 --> 00:06:26.180 first 20 terms of a geometric. NOTE CONF {"raw":[100,95,94,99,98,100]} 00:06:27.340 --> 00:06:28.030 Sequence. NOTE CONF {"raw":[79]} 00:06:29.230 --> 00:06:34.030 We can therefore rewrite this some as simply one over NOTE CONF {"raw":[100,100,100,98,100,62,99,100,85,100]} 00:06:34.030 --> 00:06:39.100 one, plus the interest rate multiplied by one minus Y, NOTE CONF {"raw":[100,100,99,100,99,100,100,100,100,68]} 00:06:39.100 --> 00:06:41.350 plus the interest rate to the power of twenty oh, NOTE CONF {"raw":[100,100,100,99,93,100,100,100,88,79]} 00:06:41.350 --> 00:06:45.100 divided by one minus one over one, plus the interest NOTE CONF {"raw":[100,100,97,100,100,100,100,100,100,100]} 00:06:45.100 --> 00:06:45.400 rate. NOTE CONF {"raw":[98]} 00:06:45.550 --> 00:06:49.540 And this is the formula for the sum of geometric NOTE CONF {"raw":[100,100,100,100,100,100,100,79,100,100]} 00:06:49.540 --> 00:06:52.690 series with 20 elements and the common ratio one over NOTE CONF {"raw":[87,100,68,100,90,99,100,100,100,100]} 00:06:52.690 --> 00:06:55.390 one plus hour in the first element, one hundred over NOTE CONF {"raw":[100,95,51,97,90,100,100,80,80,100]} 00:06:55.390 --> 00:06:55.630 one. NOTE CONF {"raw":[98]} 00:06:55.860 --> 00:06:59.590 So therefore this formula signifies that whether the project is NOTE CONF {"raw":[68,97,100,100,100,100,100,100,100,100]} 00:06:59.590 --> 00:07:04.030 worthwhile undertaking will ultimately depend not only on what are NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:07:04.030 --> 00:07:06.310 the payoffs and the costs of the project, but also NOTE CONF {"raw":[100,99,100,100,97,100,100,100,100,100]} 00:07:06.370 --> 00:07:07.330 on the interest rate. NOTE CONF {"raw":[100,100,100,94]} 00:07:08.350 --> 00:07:12.430 For example, suppose that the interest rate is five percent. NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:07:12.940 --> 00:07:16.180 If we plug in zero point zero five into our NOTE CONF {"raw":[100,100,100,100,100,100,100,100,52,100]} 00:07:16.180 --> 00:07:18.460 formula for the net present value, we are going to NOTE CONF {"raw":[100,100,99,100,100,100,100,100,100,100]} 00:07:18.550 --> 00:07:20.980 find that the net present value of the project would NOTE CONF {"raw":[100,100,100,97,100,100,100,100,100,82]} 00:07:20.980 --> 00:07:22.090 be negative. NOTE CONF {"raw":[100,100]} 00:07:22.420 --> 00:07:24.700 Two hundred and fifty four thousand pounds. NOTE CONF {"raw":[100,100,99,100,95,100,100]} 00:07:25.870 --> 00:07:28.990 And since the net present value is negative, it implies NOTE CONF {"raw":[100,100,99,99,100,100,100,100,100,100]} 00:07:28.990 --> 00:07:32.230 that the project should not be undertaken because it is NOTE CONF {"raw":[100,100,98,100,100,100,100,100,100,100]} 00:07:32.230 --> 00:07:36.120 better to deposit your money in a bank account, instead NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:07:36.400 --> 00:07:38.650 yielding the interest rate of five percent. NOTE CONF {"raw":[99,100,100,100,89,100,100]} 00:07:39.010 --> 00:07:41.860 And over the duration of 20 years, this is going NOTE CONF {"raw":[100,100,100,100,100,57,100,100,100,100]} 00:07:41.860 --> 00:07:43.730 to hold your fire profits. NOTE CONF {"raw":[100,100,100,100,98]} 00:07:43.750 --> 00:07:45.340 Then investing in the project. NOTE CONF {"raw":[97,94,100,100,100]} 00:07:46.260 --> 00:07:50.400 However, if the interest rate lasts only one percent, then NOTE CONF {"raw":[100,100,100,100,100,43,100,100,100,100]} 00:07:50.400 --> 00:07:53.190 by blackening one percent inside this formula, we are going NOTE CONF {"raw":[99,42,100,100,98,99,100,100,100,100]} 00:07:53.190 --> 00:07:55.200 to be able to calculate that the net present value NOTE CONF {"raw":[100,100,100,100,100,98,99,100,100,100]} 00:07:55.200 --> 00:07:58.140 is, in fact, positive and large, positive and equal to NOTE CONF {"raw":[100,100,100,100,93,100,100,95,100,100]} 00:07:58.440 --> 00:08:00.990 three hundred and four thousand pounds. NOTE CONF {"raw":[95,95,99,100,100,100]} 00:08:01.380 --> 00:08:03.990 Therefore, in this case, if the interest rate to slow NOTE CONF {"raw":[100,100,100,100,90,100,100,92,92,98]} 00:08:04.110 --> 00:08:08.580 the project should be undertaken because it yields better returns, NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:08:08.580 --> 00:08:11.250 then the next best option, which is to deposit your NOTE CONF {"raw":[83,100,100,100,100,100,100,100,100,100]} 00:08:11.250 --> 00:08:12.420 money in a bank. NOTE CONF {"raw":[100,100,100,100]} 00:08:13.370 --> 00:08:20.390 This brief example demonstrates the usefulness of geometric series in NOTE CONF {"raw":[100,95,100,100,100,100,100,100,78,100]} 00:08:20.390 --> 00:08:28.520 the context of economics and also demonstrates one important, you NOTE CONF {"raw":[100,100,100,100,100,100,100,86,98,100]} 00:08:28.520 --> 00:08:31.700 know, concept in economics, which is about the relationship between NOTE CONF {"raw":[100,100,99,100,100,100,100,100,100,100]} 00:08:31.880 --> 00:08:33.289 interest rates and investment. NOTE CONF {"raw":[100,100,98,90]} 00:08:33.770 --> 00:08:38.780 As we know often in macroeconomics, we assume that higher NOTE CONF {"raw":[100,100,100,100,100,100,100,100,100,100]} 00:08:38.780 --> 00:08:40.969 interest rates discourage investment. NOTE CONF {"raw":[100,100,100,100]} 00:08:42.150 --> 00:08:46.980 And the underlying logic behind this, the underlying argument behind NOTE CONF {"raw":[100,100,100,100,100,100,100,100,98,100]} 00:08:46.980 --> 00:08:50.280 this statement is exactly one based on net present value. NOTE CONF {"raw":[96,100,98,100,85,100,100,100,100,100]} 00:08:51.030 --> 00:08:54.120 As we have seen here, when the interest rates are NOTE CONF {"raw":[92,100,100,100,99,100,93,100,100,100]} 00:08:54.120 --> 00:08:59.310 low, the project was worthwhile undertaking and therefore investment should NOTE CONF {"raw":[100,100,100,100,100,99,85,100,88,100]} 00:08:59.310 --> 00:09:00.060 be undertaken. NOTE CONF {"raw":[100,100]} 00:09:00.300 --> 00:09:04.440 But atai interest rates, investment should not be undertaken. NOTE CONF {"raw":[100,45,100,95,97,100,100,100,93]}