The local amusement park was interested in the average wait time at their most popular roller coaster at the peak park time (2 p.m.). They selected 13 patrons and had them get in line between 2 and 3 p.m. Each was given a stopwatch to record the time they spent in line. The times recorded were as follows (in minutes). 118, 124, 108, 116, 99, 120, 148, 118, 119, 121, 45, 130, 118
What is the 90th percentile?
A) 100.8
B) 118
C) 130
D) 112
E) 45

Question

Quizplus · Accepted Answer

Place scores in ascending order and calculate the index = (p/100)n = (90/100) × 13 = 11.7. When the index is not an integer, round up to the next integer to obtain the index value: 11.7 rounds to 12; the 12^th value is 130.

The Local Amusement Park Was Interested in the Average Wait