Discussion of Question with ID = 030 under Percentages

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Question

If 7% of A + B = 11% of A - B, then what percent of B is A?

A

$4{1/2}$ %.

B

$5{1/2}$ %.

C

$3{1/2}$ %.

D

$3{3/4}$ %.

Soln.
Ans: a

We have been given 7% of A + B = 11% of A - B, so ${A + B}/{A - B}$ = $11/7$. By componendo and dividendo, ${(A + B) + (A - B)}/{(A + B) - (A - B)}$ = ${11 + 7}/{11 - 7}$, which gives $A/B$ = $18/4$ = ${9/2}$, which is same as: $4{1/2}$%


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