00:02
Hello, the compound interest formula is the amount after t years is equal to p times 1 plus r.
00:12
R is the rate in fractions or decimals over n where n is the periods at which the interest is compounded.
00:24
How many periods are there in one year? it is a number of periods in one year at which the interest is compounded to the power nt where t is the time in years.
00:39
In the first question we are given that the principal is 8000, t is 6, r is 5 percent and it is compounded annually so there is a only one period in one year so n equal to 1.
00:53
We have to find a.
00:56
A is equal to 8000 into 1 plus 5 percent r is equal to 0 .05, n equal to 1 so we just leave it n equal to 1 and t is equal to 6 and we when we calculate this we get this to be equal to 10 ,720 dollars 0 .77 cents approximately equal to.
01:34
In the second question we are given that at maturity the amount is 10 ,000 dollars, the rate of interest per annum was 3 percent, t was 7 years and it was interest was compounded monthly so there are 12 periods in one year.
01:54
We are asked to find what was the initial investment or what was the principal.
02:00
So the principal is equal to the amount divided by principal equal to amount divided by this whole thing which is 1 plus r by n to the power nt which would be in this case 10 ,000 divided by 1 plus r is 3 percent which is 0 .03 and n is 12 this is 0 .03 divided by 12 to the power 12 times 7 12 times 7 and this once you calculate this it comes out to be 8107, 8107 dollars and 97 cents approximately.
03:13
Since these are there are a lot of decimals where we can only give it approximations up to the nearest cent this is 97 cent...