Bunuel
Consider a class of 40 students whose average weight is 40 kgs. m new students join this class whose average weight is n kgs. If it is known that m + n = 50, what is the maximum possible average weight of the class now?
A 40.18 kgs
B 40.56 kgs
C 40.67 kgs
D 40.49 kgs
E 40.78 Kgs
Are You Up For the Challenge: 700 Level QuestionsUse the method of deviations discussed here:
https://anaprep.com/arithmetic-usefulne ... eviations/Assume that all the 40 students have weight of 40 kgs each.
Consider m = 1, n = 49. We have excess of 9 to be distributed among 41 students. So average will increase by 9/41
If m = 2, n = 48, we have excess of 16 to be distributed among 42 students. So average will increase by 16/42.
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If m = 4, n = 46, we have excess of 24 to be distributed among 44 students. So average will increase by 24/44.
If m = 5, n = 45, we have excess of 25 to be distributed among 45 students. So average will increase by 25/45 (a little bit more than 0.5 kgs)
If m = 6, n = 44, we have excess of 24 to be distributed among 46 students. So average will increase by 24/46 (the increase in average is reducing now since 24/46 is less than 24/44))
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So the average will increase at most by a bit more than 0.5 kgs. Hence answer must be (B).