8.7 Review

$X$ ~

• A $U(\mathrm{0,4})$
• B $U(\text{10},2)$
• C $N(\mathrm{2,1})$

The average wait time is:

• A 1 hour
• B 2 hour
• C 2.5 hour
• D 4 hour

• 40% of full-time students took 4 years to graduate
• 30% of full-time students took 5 years to graduate
• 20% of full-time students took 6 years to graduate
• 10% of full-time students took 7 years to graduate

The expected time for full-time students to graduate is:

• A 4 years
• B 4.5 years
• C 5 years
• D 5.5 years

The length of time to brush one’s teeth is generally thought to be exponentially distributed with a mean of $\frac{3}{4}$ minutes. Find the probability that a randomly selected person brushes his/her teeth less than $\frac{3}{4}$ minutes.

• A 0.5
• B $\frac{3}{4}$
• C 0.43
• D 0.63

Which distribution accurately describes the following situation?

The chance that a teenage boy regularly gives his mother a kiss goodnight (and he should!!) is about 20%. Fourteen teenage boys are randomly surveyed.

$X=$ the number of teenage boys that regularly give their mother a kiss goodnight

• A $B(\text{14},0\text{.}\text{20})$
• B $N(2\text{.}\mathrm{8,2}\text{.}\text{24})$