Question

On each trial of an experiment, a subject is presented with a constant soft noise, which is interrupted at some unpredictable time by a noticeably louder sound. The time it takes for the subject to react to this louder sound is recorded. The following list contains the reaction times (in milliseconds) for the

16trials of this experiment:

236, 217, 261, 271, 222, 186, 235, 202, 296, 226, 257, 269, 229, 250, 193, 231

Find 20^th and 75^th percentiles for these reaction times.

Answer 1

SOLUTION-

ARRANGING THE DATA IN ASCENDING ORDER, WE GET:

186, 193, 202, 217, 222, 226, 229, 231, 235, 236, 250, 257, 261, 269, 271, 296

NOW, SAMPLE SIZE(N) = 16

TO FIND 20TH PERCENTILE-

INDEX = 0.20*16 = 3.2 = 3(ROUNDING OFF TO NEAREST INTEGER)

SO 20TH PERCENTILE = 202( 2 OBSERVATIONS LIE BELOW 202)

TO FIND 75TH PERCENTILE-

INDEX = 0.75*16 = 12

SO 20TH PERCENTILE = 261( 12 OBSERVATIONS LIE BELOW 261)

****IN CASE OF DOUBT, COMMENT BELOW. ALSO LIKE THE SOLUTION, IF POSSIBLE.

answered by: anonymous