Practise interpreting confidence intervals, linking them to claims and reasoning about whether intervals contain the true mean.
A garden centre sells bags of stones and large bags of gravel.
The weight, X kilograms, of stones in a bag can be modelled by a normal distribution with unknown mean μ and known standard deviation 0.4
The stones in each of a random sample of 36 bags from a large batch is weighed. The total weight of stones in these 36 bags is found to be 806.4 kg
Using your answer to part (a), comment on the claim made by the manufacturer.
The weight, Y kilograms, of gravel in a large bag can be modelled by a normal distribution with mean 850 kg and standard deviation 5 kg
A builder purchases 10 large bags of gravel.
22.5 is within the confidence interval
So no reason to doubt the manufacturers claim
B1 ft
dB1 ft