Question 1
Paper 2, calculatorMedium6 marksThe waiting times, in minutes, for a sample of eight customers at a repair desk were
12, 14, 14, 16, 18, 19, 21, 26.
(a)[2]
Use your GDC to determine the sample mean and sample standard deviation, correct to three significant figures.
(b)[1]
Hence find the sample variance, correct to three significant figures.
(c)[3]
For a later report, 3 minutes is subtracted from every waiting time in the sample. A supervisor claims that the standard deviation will therefore also decrease by 3 minutes.
Determine the new sample mean and standard deviation, and comment on the supervisor’s claim.