Explanation for Question 37 From the Math (Calc) Section on the Official Sat Practice Test 1
So question number 37 asks us for the value of X in the expression. 2 So we need to go back up to this equation or those questions and 3 read along here. And it says that Jessica opened a bank account that earns 4 2% interest compounded annually. 5 Her initial deposit was a hundred dollars and she uses this expression to 6 find the value of the account after two years. 7 Right? So here's the expression that we're working with 100 x-rays to the T 8 and we want to know what X is. And so if you remember the, 9 um, the equation like this general form of the equation for when we're talking 10 about, um, percents and exponential growth, 11 especially in bank accounts, we should know that what is here in this parentheses 12 is our rate, right? The rate of growth, 13 or sometimes the rate of decline and this case, 14 the rate of growth. 15 Um, and we know that we're getting 2%, 16 right? So we're taking our starting point, 17 which we call one, and then we're adding 2% to that, 18 right? So the X is going to have to be 1.02, 19 because that shows that we're growing by 2% every year. 20 Um, so just to show you that general forum, we know that Y is 21 equal to a R raised to the T where a is your initial starting 22 point. So like your initial amount, which is why we put the 100, 23 there are, is your rate, 24 which we get is one plus or minus the percent. 25 Right? So if we were declining by 2%, 26 we would do one minus 0.02. But since we're increasing by 2%, 27 we do one plus 0.02, and then your exponent is your time. 28 And since we were asked for what's in the parentheses, 29 we were asking, or that we were being asked about the rate, 30 which is going to be 1.02.