Last year Department Store X had a sales total for December that was 4 times the average (arithmetic mean) of the monthly sales totals for January through November. The sales total for December was what fraction of the sales total for the year?
(A) 1/4 (B) 4/15 (C) 1/3 (D) 4/11 (E) 4/5
Ans. should be B (4/15) Consider x is avg arithmatic mean for 11 month i.e. Jan to Nov. (Total sale for 11 months is 11x. Dec sale is 4 times the mean of remaining 11 months, i.e. 4x. So sales total for Dec / total sales ((sales for jan-Nov) + (Sales ofr Dec)) = 4x/(4x+11x) = 4x / 15x so result comes out 4/15. Let me know if answer is correct.
Also refer for DS queries I have posted and let me know answers if U can solve.
Great explanation. I think people may get a bit confused with this one and just say it’s 4/12 or 4/11 because that sounds about right, but once you work it out it’s pretty easy. That’s why it’s important to go slow and not too fast, and make sure to work out every question until you’re certain about the answer.
Let us suppose the total sale from jan-nov is x. and hence the avg is x/11. therefore sale for december is 4x/11. Total sale for year is x+4x/11 = 15x/11. Hence, the sale for dec/total sale is (4x/11)/15x/11 = 4/15.
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