1. In a lot of n components, 30% are defective. Two components are drawn at random and tested. Let A be the event that the first component drawn is defective,….

## Find the probability mass function of X

1. Determine whether each of the following random variables is discrete or continuous.

a. The number of heads in 100 tosses of a coin.

b. The length of a rod randomly chosen from a day's production.

c. The final exam score of a randomly chosen student from last semester's engineering statistics class.

d. The age of a randomly chosen Colorado School of Mines student.

**e. **The age that a randomly chosen Colorado School of Mines student will be on his or her next birthday.

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**2. **** **A survey of cars on a certain stretch of highway during morning commute hours showed that 70% had only one occupant, 15% had 2, 10% had 3, 3% had 4, and 2% had 5. Let X represent the number of occupants in a randomly chosen car.

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a. Find the probability mass function of X

b. . Find P(X ≤ 2).

c. Find P(X > 3).

d. Find μX .

**e. **Find σX .