1.The following table shows the number of correct answers and the cumulative relative frequency for those scores in the class.

value cumulative relative frequency

2 0.13

3 0.55

4 0.925

5 1.000

What is the probability that a randomly selected student from the class scored a 3 on the short quiz?

2.You are interested in the number of English-speaking people on the planet who want to play a new kind of online video game.You asked 300 college students if they were interested in playing video games, 100 said yes, and of them 20 preferred your game to an existing game that is widely used. How many people were in the sample?

3.A random variable called L is defined by the following table, but one of the relative frequencies is missing:

value relative frequency

-5 0.17

0 0.11

1 0.23

3 -

8 .15

i). What is the missing value in the list of relative frequencies for random variable L?

ii). What is the probability that a randomly selected item from random variable L will be greater than 0 and less than or equal to 3?

iii). What is the expectation of random variable L?

iv). What is the variance of random variable L?

4.Which distributions below are discrete?

a. the normal distribution and the Poisson distribution.

b. the Poisson distribution, the binomial distribution, and the uniform distribution.

c. the binomial distribution and the exponential distribution.

d. the Poisson distribution, the binomial distribution, and the normal distribution.

e. none of the answers above are accurate

5.At a small store, a customer enters the front door on average every 8 minutes.A prior study indicated that the time between customers entering the front door during weekdays follows an exponential distribution.What is the probability that the time between customers entering the store on a weekday will be less than or equal to 7