Explanation for Question 9 From the Math (Calc) Section on the Official Sat Practice Test 9
Question nine provides us with this table and it reads on Tuesday, 2 a local gas station had 135 customers. 3 The table above summarizes whether or not the customers on Tuesday purchased gasoline, 4 a beverage, both or neither based on the data in the table. 5 What is the probability that a gas station customer is selected at random on 6 that day did not purchase gasoline. 7 So this is a probability question. 8 And the first step to this is figuring out what group of people we're 9 looking at. It asks us about a gas 10 station, customer selected at random. 11 So any gas station customer is going to be included in this. 12 Our sample size is the whole 135 people that came that day. 13 And we want the people that did not purchase gasoline, 14 gasoline, not purchased. If we follow this row all the way to 15 the end, we can see that 50 people out of that total 135 16 did not purchase gasoline. We're not talking about the beverages for this case. 17 It doesn't mention the probability of them buying a beverage as well as gasoline 18 or anything like that. So don't let those numbers distract you. 19 We're just going to go with 50, over 135 for our answer, 20 which is choice D.