To determine the average speed of cars along a certain road, a random sample of 100 cars is taken and the mean speed in

[answerhappygod]

To determine the average speed of cars along a certain road, a
random sample of 100 cars is taken and the mean speed in the sample
is found to be 58.4 mph. If the true standard deviation of the
speeds is known to be 15 mph, find a 95% confidence interval for µ,
the true average speed. [8 marks] (b) A manufacturer of sports
equipment has developed a new synthetic fishing line that is
claimed to have a mean breaking strenght of 8 kg. To test the
manufacturer’s claim, that is, whether the mean breaking strenght
is actually 8 kg or not, a sample of 12 lines is tested. The sample
had a mean breaking strength of 7.8 kg and a standard deviation of
0.5 kg. Write down your null hypothesis and alternative hypothesis
and then, using an appropriate distribution, test your null
hypothesis against your alternative hypothesis at the 5%
significance level.