Originally Posted by

**laikarting** 2 questions.

[snip]

2. a sales contract between a manufacturer and a buyer requires 20 towels to be subjected to a water absorption test. if no more than one towel fails the test, the batch is accepted. if two or three towels fail the test, an additional 20 towels are tested. the batch is then accepted if 3 or less( out of 40) fail the test. otherwise, the batch is rejected.The lengths of 20 towels are measured and if the mean length is less than a value a specified in the contract, the batch is rejected. what should be the value of a to give a probability of 0.99 of accepting a batch with mean length 106mm and standard deviation 6mm?

Your helps to solve these two questions are highly appreciated, thank you!