Explanation for Question 13 From the Math (Calc) Section on the 2019 May Sat
Question 13 asks the table above gives the number of us presents from 2 1789 to 2015, 3 whose age at the time they first took office is within the interval listed 4 of those presidents who were at least 50 years old when they first took 5 office. What fraction were at least 60 years old. 6 So to answer this question, 7 we're going to need to come up with a fraction where the denominator is 8 the group of people in the sample. 9 And the numerator is the more specific group that we want to know the 10 fraction of. So first let's find what percent or what group of 11 people we're taking the sample from. And that information is right here of 12 those presents, who are at least 50 years old when they first took office. 13 So all we have to do is look at this graph right here at 14 the top, and we need to look at the number of people 15 who took office when they were 50 years old or older. 16 Um, so all we need to do is add together these four different, 17 uh, rows. So 13 plus 11 plus 18 seven plus two, 19 and that gives us 33. 20 So we know that the denominator is going to be 33 to find the 21 numerator and we then need to find out how many were at least 60 22 years old. So again, 23 let's go to the chart at this time, our group is getting smaller. 24 We're only looking at 60 down these two numbers. 25 So seven plus two is equal to nine and that's our numerator. 26 So an important thing to take note of here is the test. 27 Actually, miswrote the answer choices. 28 So it's actually none of these four answer choices. 29 Our final answer is nine out of 33.