Pew Research Center surveyed adults who were 18–64 years old and had their own children under age 18 living in their household in 2015 on the amount of time spent on various activities. The results indicated that dads spent an average of 9 hours per week doing housework (compared to 18 hours per week for moms). Assume the hours per week doing housework follows the normal probability distribution with a standard deviation of 3.2 hours per week and that these statistics still hold true.

a. What is the probability that a randomly selected dad from this group spent

1. fewer than 11 hours doing housework this week?

2. more than 12 hours doing housework this week?

3. between 7 and 9 hours doing housework this week?

4. between 8 and 15 hours doing housework this week?

b. Use Excel to confirm the answers in part a.

c. How many of hours of housework will a dad in this group perform if he is in the 70th percentile?