Answer:
a)

b)

Step-by-step explanation:
We have to build appropriate null and alternate hypothesis for the given scenarios.
a) Population mean, μ = $62,500 per year
The market research wants to find whether the mean household income of mall shoppers is higher than that of the general population.

We would use one-tail(right) test to perform this hypothesis.
b) Population mean, μ = 2.6 hours
The company want to know the average time to respond to trouble calls is different or not.

We would use two-tail test to perform this hypothesis.
10x2= 20
20x3.14= 62.8
the circumference of the disc is 62.8
Answer
3 3/8 ÷ (3/4) = (9/2) = 4 ½
Explanation
We are asked to evaluate 3 3/8 divided by 3/4 using cross multiplication algorithm.
The algorithm will need us to put the mixed fraction in definite fraction form (improper fraction) and to evaluate the division, we change the division sign into multiplication sign and the fraction after the division sign changes into its reciprocal.
3 3/8 = (27/8)
(3 3/8) ÷ (3/4)
= (27/8) ÷ (3/4)

Hope this Helps!!!