Question

2.- Of the 40,000 people who are constructing a building in the state of California, a random sample of 522 was seen and their daily income was investigated. The following table shows the results.

Income X	Number of People
50 to less than 60	75
60 to less than 70	97
70 to less than 80	135
80 to less than 90	155
90 to less than 100	60
Total	522

Construct a 90% confidence interval for the daily income of the total population of people.

Answer 1

Sample mean =75.5364

n=522

Df= 521

CRITICAL value( at alpha/2= 0.05)=1.648

90%confidence interval=(xbar±critical value*sd/√522)

=(75.5364±1.648*12.3178/√522)

=(74.6479,76.4249)

Thanks!