Maths Statistics QuestionWatch this thread
The weight of crisps in each packet, M grams follows a normal distribution with mean 40 g
Given that 20% of packets contain more than 42 g of crisps,
(a) Find, to 2dp, the value of k such that P(k < A < 40) = 0.40
Eighteen packets of crisps are selected at random.
(b) Find the probability that fewer than 3 of these packets contain more than 42 g or crisps.
A second machine makes larger packets of crisps of weight Y grams, where Y is normally distributed with standard deviation 7.5 g
A manager believes that the mean weight of crisps put into each packet is greater than 175 g
A random sample of 10 packets from this second machine was found to have a mean weight of crisps of 178.5 g
(c) Test whether or not the mean weight of crisps in larger packets, filled by the second machine, is greater than 175 g
State your hypotheses clearly and use a 5% level of significance.
You are then able to do part a with the mean and standard deviation you have worked out.
Part c is hypothesis tests