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1. Which of the following values cannot be a probability? Select all that apply.

ID: 3170541 • Letter: 1

Question

1. Which of the following values cannot be a probability? Select all that apply.

a. -0.001

b. 0.5

c. 1.001

d. 0

e. 1

f. 25%

2. A teacher asks 25 of her students to write down their favorite color. The results are presented below:

Color     frequency

Red         8

Blue      12

Green   5

If a student is selected at random from the above group of 25, what is the probability that this student likes the red color?

3. The table below shows students distribution per grade in a school.

Grade    frequency

1             50

2              30

3             40

4             42

5             38

6             50

If a student is selected at random from this school, what is the probability that this student is in fourth grade?

4. The time taken to fully service a car at XYZ garage is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be fully serviced in this garage in less than 19.5 hours?

Explanation / Answer

1. Probability is always between 0 to 1 so a and c are not probability values

2. P(Red)=8/25=0.32

3. P(4th grade)=42/250=0.168

4. P(x<19.5)=P(z<19.5-20/2)=P(z<-0.25)=0.4013