[Video] Q38: The owner of the good deals store opens a new store across town. for the new store, the owner estimates that, during business hours, an average of 90 shoppers per hour enter the store and each of them stays an average of 12 minutes. the average number of shoppers in the new store at any time is what percent less than the average number of shoppers in the original store at any time? (note: ignore the percent symbol when entering your answer. for example, if the answer is 42.1%, enter 42.1)

Explanation for Question 38 From the Math (Calc) Section on the Official Sat Practice Test 3

Now for number 38, we're going to continue to use the same equation. 2 End equals R times T. And we see that 90 is our R so 3 that's 90 shoppers per hour. And our time is 12 minutes. 4 However, we have to do a little bit of converting here because we should 5 notice that one of our numbers has hours and one has minutes, 6 right? So we need to convert that minutes to hours. 7 And the way that we'll do that is by dividing by 60, 8 because that allows our minute units to cancel. 9 It allows our, our units to cancel and just leaves us with shoppers. 10 And when you multiply these across, you get 18, 11 right? And so if we want to find what percent less, 12 the average number is from the original store, 13 which was 45, we first need to figure out what percent of 45 18 is. 14 Now, if you plug in 18, over 45 into your calculator, 15 you'll get 40%. And so perhaps you were attempted to answer 42, 16 this, to this question, but that's not going to be correct here because we're 17 trying to find what percent less, the average number is not what percent of 18 the average number is, right? So if I am 40% of the number, 19 then I've lost 60%, right? 20 Because one minus 0.4 will give us 0.6. 21 And so in fact, we're going to be 60% less than the original number.