[Video] Q9: Markela opens a bank account that earns interest at a rate of 2% compounded annually. she puts $200 in the account when she opens it and does not make any more deposits into or withdrawals from the account for 2 years. if the amount of money in the account after 2 years is given by the expression 200(1.02)^2, which of the following expressions gives the amount of money in the account after 1 year?

Explanation for Question 9 From the Math (Calc) Section on the 2020 October Sat

So can you question nine, we can see that Markella opens a bank account 2 and she gets an interest rate of 2% compounded annually. 3 And so one of the key things here is annually. And if you remember 4 the equation, you'll know that we have an exponent, 5 right. That has to do with your compounding. 6 The exponent goes here, and that is how many times you actually get 7 your interest per year. And so annually means that she gets interest once, 8 once a year. So her exponent is only going to be one. 9 And the only one that has an exponent of one, 10 right? The invisible one is a and B. 11 These have an exponent of two, which would be by annually or twice 12 a year. And then we could see that she puts $200 into her account. 13 So she started with $200 and we want to choose the answer that shows 14 that now this number in front of the parentheses is always your initial 15 starting point. And since she put in $200 to start with, 16 we need to have a 200 in the front. 17 So that's why the best answer is B.