Explanation for Question 2 From the Math (Calc) Section on the 2017 May Sat
Let's read a question to either summer job, 2 Paula earns the same amount of money for each hour. 3 She works. If she runs $240 for working 20 hours, 4 how much does she earn for working five hours? 5 So since it says, she makes the same amount of money per hour, 6 we can make a proportion comparing hours and 7 money. She earns. So proportions doesn't matter what you, 8 what order you write it. As long as you have the top and 9 the bottom have to apply to the top and the bottom of the other 10 side. So if the top is in hours, 11 the other numerator has to be in hours. 12 If the denominator is in money or dollars. 13 So does the other denominator, they just have to be consistent. 14 So we're going to say that for 20 hours, 15 she makes $240. 16 You could flip that. It doesn't matter. As long as this next side is 17 consistent. 18 So for five hours, how much does she make? 19 This is what we're trying to find out. So we're going to put an 20 X in the denominator. Now we have a proportion and to solve 21 it, all we have to do is cross multiply. 22 So we get 20 times X equals five times, 23 240. Again, 24 I'm going to be using my calculator and 240 times five 25 is 1200. So now we have 20 26 X equals 1200 and to solve for X, 27 all we do is we divide by 20 to get X by itself. 28 And that gives us 60. 29 So X equals 60, which means that in five hours she 30 makes $60.