The company financial officer was interested in the average cost of PCs that had been purchased in the past six months.She took a random sample of the price of 10 computers,with the following results.
$3,250,$1,127,$2,995,$3,250,$3,445,$3,449,$1,482,$6,120,$3,009,$4,000
What is the 90^th percentile?

Question

Quizplus · Accepted Answer

The 90th percentile is the value below which 90% of the data falls. When the data is ordered, the 90th percentile falls between the 9th and 10th values. The ordered data is: $1,127, $1,482, $2,995, $3,009, $3,250, $3,250, $3,445, $3,449, $4,000, $6,120. The 9th value is $4,000 and the 10th is $6,120. The 90th percentile is calculated as 0.9*(10+1) = 9.9, which is between the 9th and 10th values, so we interpolate: $4,000 + 0.9*($6,120 - $4,000) = $5,060.

The Company Financial Officer Was Interested in the Average Cost