Explanation for Question 37 From the Math (Calc) Section on the Official Sat Practice Test 4
So now for number 37, um, 2 we're looking at this paragraph right here, which says the stock price of one 3 share in a certain company is $360 today, 4 right? And then the stock and that analyst, 5 uh, believes that the stock will lose 28% of its value every week. 6 And so we write this equation and so we need to know what should 7 the analyst use for R and what's important to notice about this equation and 8 that is that it's written as exponential growth or decay. 9 So we got V is equal to 360 or T. 10 And so the general form of this is Y is equal 11 to a times, our rates to the T, 12 where, where Y is your final amount, 13 a is your initial amount, R is your rate and T 14 is time and rate refers to the percentage of growth or increase. 15 So if you're having growth, your RN needs to be greater than one. 16 And if you're having the K or decreasing your R needs to be less 17 than one. And so in this case, 18 we're losing 28%, right? 19 So what I have needs to be less than one. 20 So to find my R I do one minus 0.28, 21 100% minus the 28% that I'm going to lose. 22 And that gives us 72%. But remember, 23 this is written as a decimal. So our answer then to number 37 is 24 going to be a 0.7 to not point 75. 25 All sorry. Answer is 0.72, because 100% minus 28% leaves 26 us with 72%.