Mathematics (AS & A Level) · Oct / Nov 2016 · Paper 71 · 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.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
7(i)[5]
7(ii)[5]
7(iii)[1]
Make a free account to save your answers and see your weak topics and ask the AI why a wrong answer is wrong.