Bunuel wrote:

If 95% of the residents of Coral Estates live in private homes and 40% of these live in air-conditioned homes, what percent of the residents of Coral Estates live in air-conditioned homes?

(A) 3%

(B) 3.8%

(C) 30%

(D) 38%

(E) 40%

Since the calculation is straightforward, we'll just do it.

This is a Precise approach.

The percent of people who live in a home that is both private and air-conditioned is 95%*40%.

Since 10% of 40% is 4$ then 5% of 40% is 2%. So, 95% of 40% is (100%-5%)*40% = 40% - 2% = 38%

(D) is our answer.

Important note: To answer the question we had to assume that only people in private homes have air-conditioning, otherwise our number could be higher.

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