Mathematics (AS & A Level) · Oct / Nov 2016 · Paper 72 · Question 7
9709
As printed in the paper
The question as text
In the past the time, in minutes, taken for a particular rail journey has been found to have mean 20.5 and standard deviation 1.2. Some new railway signals are installed. In order to test whether the mean time has decreased, a random sample of 100 times for this journey are noted. The sample mean is found to be 20.3 minutes. You should assume that the standard deviation is unchanged.
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7(i)[5]
7(ii)[5]
7(iii)[1]
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