00:01
Alright, so in this particular problem you are asked to find the interest given in the following scenario.
00:09
You've got $3 ,000 principal that you're investing.
00:12
Your interest rate is 2 .25%.
00:16
You're leaving it there for 10 years and it's compounded monthly.
00:20
So this is key right here.
00:23
We're looking for compound interest.
00:27
So to find the amount that we have, the formula for compound interest, the amount that we have is equal to the principal, the amount that we start out with, times 1 plus the rate divided by the number of times compounded raised to the number of times compounded times the length of time that we keep it there.
00:55
So this is our p, this is our r, this is our t, and our n comes from here.
01:04
In this case compounded monthly, so n equals 12.
01:10
So then we're just going to substitute in the amount that we have is equal to our principal times 1 plus our rate.
01:24
We have to write that as a decimal, so we're going to want to write it like that, changing that percent to a decimal, so .0225 divided by 12 since we're compounding it 12 times a year, monthly, and then that's raised to the 12 and we're leaving it there 10 years.
01:45
So 12 times 10.
01:48
And then we just calculate this.
01:52
So we're going to go to our calculator.
01:55
Let me go a little bit.
01:56
Alright, so we go to the calculator here and we say 3000 times 1 plus .0225 divided by 12, and then we're going to take that and raise that entire quantity to the 12 times 10.
02:36
So that gets us $3 ,756 .18.
02:45
$3 ,756 .18.
02:56
And we started with $3 ,000, so the amount of interest that we earn is $756 .18.
03:12
Now the second part of this problem says, okay, suppose we have compounded interest again, we are saving for a $40 ,000 down payment.
03:21
This time we want to know how much we need to invest.
03:24
If our rate is 6%, our time equals 12 years, we're compounding quarterly, so that means n equals 4...