Detailed steps required

1.What is the proportion of customers who buy service plans when they buy a computer? To find out, you surveyed 166 customers and found that 53 purchased the service plan. What is the upper boundary of 90% confidence interval for the population proportion? Use Excel and round your answer to two decimal places. Give the answer as a decimal percent (that is, for 10%, give 0.1).

2. Using Excel, find the right-tail probability corresponding to the following t value. Round the answer to 4 decimal places. t = 1.456. There are 7 degrees of freedom.

3. Consider the following test performed with the level of significance 0.05: H0:u>=100 Ha:u<100 A random sample of size 31 is obtained from a normally distributed population. The population standard deviation is equal to 39.5. The sample mean happened to be 95.4. For this hypothesis test, what will be the critical value (the relevant z-alpha)?

Hint: Watch the sign - the critical value can be negative or positive. Round the answer to three decimal places.