Chapter 13.6, Problem 5CYP

A.

To determine

To determine probability of given event.

Answer to Problem 5CYP

Probability is $0.1225$ or 12.2%

Explanation of Solution

Given information :

Atleast two of them use their cell phone while driving.

Total motorists = 100

35% use their cell phone.

65% don’t use cell phone.

Probability that two of them use their cell phones $=\frac{35}{100}\cdot \frac{35}{100}\cdot \frac{65}{100}$

Probability that all use their cell phone $=\frac{65}{100}\cdot \frac{35}{100}\cdot \frac{35}{100}$

Now the probability that at least two of them use their cell phone is,

P(at least two use phone ) $=\frac{35}{100}\cdot \frac{35}{100}\cdot \frac{65}{100}+\frac{65}{100}\cdot \frac{35}{100}\cdot \frac{35}{100}=0.1225$ or 12.2%

B.

To determine

To determine probability of given event.

Answer to Problem 5CYP

Probability is $0.4225$ or 42.2%

Explanation of Solution

Given information :

No more than one use their cell phone.

Total motorists = 100

35% use their cell phone.

65% don’t use cell phone.

Probability that one of them use their cell phones $=\frac{35}{100}\cdot \frac{65}{100}\cdot \frac{65}{100}$

Probability that no one use their cell phone $=\frac{65}{100}\cdot \frac{65}{100}\cdot \frac{65}{100}$

Now the probability that not more than one use their cell phone is,

P(not more than one ) $=\frac{35}{100}\cdot \frac{65}{100}\cdot \frac{65}{100}+\frac{65}{100}\cdot \frac{65}{100}\cdot \frac{65}{100}=0.4225$ or 42.2%