Question

The average area of a bedroom in a home is 219 square feet with a standard deviation of 32.5 square feet. What is the largest a bedroom can be and be among the smallest 25% of bedrooms in a home?

Answer 1

197.095

Explanation:

Mean, m = 219 ft²

Standard deviation, s = 32.5 ft²

For a bedroom to be among the smallest 25%

P(x < Z) = 0.25

From Z probability calculator, this corresponds to a Zscore of - 0.674

Recall :

Zscore = (x - m) / s

x = bedroom size

-0.674 = (x - 219) / 32.5

-0.674 * 32.5 = x - 219

-21.905 = x - 219

x = - 21.905 + 219

x = 197.095

Hence, the largest a bedroom can be and still be among the smallest 25% is 197.095