The distribution of the time taken to run 1000 metres by users of a treadmill in a sports centre has mean 7.2 minutes and standard deviation
2.045 minutes.
1 Choose the option that is closest to the probability that the mean time taken to run 1000 metres for a sample of 30 users will be more than 8 minutes.
Options for Question 1
A 0.0160 B 0.2000 C 0.2486 D 0.8003 E 0.8030 F 0.8106
2 Choose the option that gives an approximate range of values,in minutes, symmetric about the mean, within which the meantime taken to run 1000 metres for approximately 95% of samples of 30 users will lie.
Options for Question 2
A (6.584, 7.816) B (6.469, 7.931) C (3.192, 11.208) D (6.640, 7.760) E (7.066, 7.334) F (4.088, 11.312)
1. When averagng over 30 users, the standard deviation of the mean is 2.045/sqrt(30)
Using a normal distribtuobn calculaor, I get
A. 1.6%
2. B. (6.469, 7.931)