Question

26. The population mean annual salary for flight attendants is $56,275. Assume annual salaries for flight attendants are normally distributed, with a standard deviation of $1,720.

1. We are flying from Las Vegas to Los Angeles, and we randomly select one flight attendant on our flight and ask him about his annual salary. What is the probability that this randomly selected flight attendant makes an annual salary less than $57,500?
   
   
   
2. We randomly sample 30 flight attendants. What is the probability that their mean annual salary is more than $56,000?
   
   
   

c. We randomly sample another 48 flight attendants. What is the probability that their mean annual salary is between than $55,800 and $57,000?

Answer 1

Given that

(a)

The z-score for X = 57500 is

Using z table, the probability that this randomly selected flight attendant makes an annual salary less than $57,500 is

(b)

The z-score for is

Using z table, the probability that their mean annual salary is more than $56,000 is

(c)

The z-score for is

The z-score for is

Using z table, the probability that their mean annual salary is between than $55,800 and $57,000 is