At a certain auto dealership, 500 cars were sold last week. If a different number of cars were sold on each of the seven days, did the dealership sell at least 50 cars on Friday of that week?
(1) On Monday, the dealership sold 75 cars, which was the third-highest number of cars sold on any day that week.
(2) On Saturday, the dealership sold 77 cars, which was the highest number of cars sold on any day that week.
A) M = 75, from the other 5 days
let 2nd highest be 76 and highest be 77
take the 6 days other than fri as (in increasing order) : 72, 73, 74, 75, 76, 77
Total is less than 250, hence Fri can be more than 50, but need not be. If the max number of car sold exceeds say its 100, and the rest remain the same, Fri will be less than 50 ----> not sufficient
B) as proved above, if highest is 77 then least is more than 50. -----> sufficient (B)
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