Use thus example to answer the next two questions. A recent study of the lifetimes of laptop computers found the average is 23.4 months. The population standard deviation is 6.8 months. If a company provides a sample of 25 employees with a laptop computer, find the following probabilities assuming laptop computer life is a normally distributed variable:

The probability that the mean lifetime of these laptop computers will be less than 23 months.

The probability that the mean lifetime of these laptop computers will be between than 23.8 months and 24.3 months

Which of the following is not a valid null hypothesis? 1) Ho:u >/= 0

2) Ho: u

3) Ho: not equal 0