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Paper 4 (9164, Section A) · June 2007 · Hypothesis Testing

A driver records the times (minutes) taken to complete a 50 km lap over 30 laps: Time 23 (frequency 3), 24 (7), 25 (8), 26 (6), 27 (3), 28 (2), 29 (1). What is the sample mean lap time, to 1 decimal place?

Model answer

25.3

Also accepted: 25.3 minutes

Explanation

\sum fx = 3(23)+7(24)+8(25)+6(26)+3(27)+2(28)+1(29) = 759

. With

n=30

,

\bar x = 759/30 = 25.3

minutes.

Derived from ZIMSEC Maths Paper 1, June 2007, Q10 (Statistics)

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