Show formula and calculation. ANSWER QUESTION 1,3,5 ONLY

EXERCISES A study is conducted in a company that employs 800 engineers. A random sample of 50 1 . engineers reveals that the average sample age 34.3 years and standard deviation 8 years Construct a 98% confidence interval to estimate the average age of all the engineers in the company. 2. A random sample of 100 teachers in a large metropolitan area revealed a mean weekly salary of RM1948 with a standard deviation of RM2662. Construct a 95% confidence interval on average weekly salary of all teachers inn the metropolitan area and interpret its meaning. 3 The customers' shopping time at a local supermarket is known to have a normal distribution with standard deviation 16 minutes. The average shopping time from a random sample of n = 25 selected customers is 33 minutes. Construct a 99% confidence interval for u , the true average shopping time per customer. Suppose the following data is selected randomly from a population of normally distributed values. 2 5 2 4 2 1 3 Construct a 99% confidence interval to estimate the population average / x = 2.14, s =1.2924, n =14 5. The following data are about the sales revenue achieved at a certain location. Sales Revenue A B C 12 8 10 10 8 8 10 6 6 12 8 8 10 10 10 Obtain a 90% confidence interval for the mean sales revenue for location A. x =10.8, s = 1.0955, n = 5