[Video] Q37: Little’s law can be applied to any part of the store, such as a particular department or the checkout lines. the store owner determines that, during business hours, approximately 84 shoppers per hour make a purchase and each of these shoppers spends an average of 5 minutes in the checkout line. at any time during business hours, about how many shoppers, on average, are waiting in the checkout line to make a purchase at the good deals store?

Explanation for Question 37 From the Math (Calc) Section on the Official Sat Practice Test 3

Now from number seven, when we look at this problem, 2 we see that we're talking about 84 shoppers per hour, 3 and this is a rate, right? So that's going to be our R is 4 84 shoppers per hour. But if we look at the time, 5 it says five minutes. And so if we put our time in his five 6 minutes, you might be tempted to just multiply these across. 7 However, what we need to notice is that our ours in terms of hours 8 and our time is in terms of minutes. And so these are different. 9 We need both of these to both be in terms of hours. 10 So to convert that minutes to hours, I need to divide the whole thing 11 by 60, because that allows our minutes to cancel, 12 which will leave us with the hours to cancel. 13 It'll just give us our number of shoppers, 14 which is what we want. And so when you do 84 times five divided 15 by 60 you'll get seven, which shows us that our end value is seven 16 shoppers.