30. Given problem : You deposited 2 000 dollars, then you will earn 6% simple interest.
Question: How long will it become 2 600 dollars.
Well, you didn’t mention if it’s an annual interest or monthly interest.
But let’s say that it’s a monthly interest, then let’s start solving:
=> 2000 Is the original amount + 6% interest
first month = 2000 * .06 = 120
=> 2000 + 120 = 2120
2nd month = 2120 *.06 = 127.2
=> 2120 + 127.2 = 2247.2
3rd month = 2247.2 *.06 = 134.832
=> 2247.2 + 134.832 = 2382.032
4th month = 2382.032 * .06 = 142.92192
=> 2382.032 + 142.92192 = 2524.95392
5th month = 2524.95392 * .06 = 151.497
=> 2524.95392 + 151.497 = 2676.45
Thus, on the fifth month she will earn this amount.
You are expected to memorize the general shape of the sine function, including where the peaks and zero crossings are. The graph shows you the value of sin(270°) = -1