Question 1

Paper 1, no calculatorMedium6 marks

The histogram in Figure 1 shows the response times, xx seconds, for 32 service calls. The standard deviation of these response times is 6.46.4 seconds.

010203040506002468101214Response time, x (s)Frequency
(a)

State the modal class and estimate the mean response time.

[3]
(b)

For each response time xx a service index yy measured in index units, is defined by

y=2(x−3).y=2(x-3).

Hence, using your estimate from part (a), determine the estimated mean and the standard deviation of yy

[3]

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