COMM 215 Assignment 06 & 7 Exam with
Accurate Solutions
Which of the following statements about the binomial distribution is not correct?
Ans: The random variable of interest is continuous.
9. The probability distribution of X is
X P(X)
3 1/8
4 1/8
5 3/8
6 3/8
What is the expected value of X?
Ans: 5 ( 3*1/8+4*1/8+5*3/8+6*3/8) = 5
10. For a random variable X, the mean value of the squared deviations of its values
from their expected value is called its . Variance.
11. The internal auditor for your company believes that 10 percent of your invoices
contain errors. To check this theory, 20 invoices are randomly selected, and 5 are
found to have errors. What is the probability that of the 20 invoices selected, 5 or
more would contain errors if the theory is valid?
,12. A car wash loses $30 on rainy days and makes $120 on days when it does not
rain. If the probability of rain is .15, calculate expected profit for the car wash.
13. If you were asked to play a game in which you tossed a fair coin three times and
were given $2 for every head you threw, how much would you expect to win on
average?
P(Head on any toss) = 1 /2
So expected number of heads in 3 tosses = 3*1 /2 = 1 .5
Hence,
Winning amount = 1 .5*2 = $3
14. X has the following probability distribution P(X).
X 1 2 3 4
P(X) 0.1 0.5 0.2 0.2
Compute the variance value of X.
, 15 A total of 50 raffle tickets are sold for a contest to win a car. If you purchase one
ticket, what are your odds against winning?
Total number of Tickets=50
If we purchase one ticket ,then
P(winning a car)=P= 1 /50
pobability againist winning a car= 1 -P= (1 -1 /50)=49/50.
16. The mean of the binomial distribution is equal to. Np
Accurate Solutions
Which of the following statements about the binomial distribution is not correct?
Ans: The random variable of interest is continuous.
9. The probability distribution of X is
X P(X)
3 1/8
4 1/8
5 3/8
6 3/8
What is the expected value of X?
Ans: 5 ( 3*1/8+4*1/8+5*3/8+6*3/8) = 5
10. For a random variable X, the mean value of the squared deviations of its values
from their expected value is called its . Variance.
11. The internal auditor for your company believes that 10 percent of your invoices
contain errors. To check this theory, 20 invoices are randomly selected, and 5 are
found to have errors. What is the probability that of the 20 invoices selected, 5 or
more would contain errors if the theory is valid?
,12. A car wash loses $30 on rainy days and makes $120 on days when it does not
rain. If the probability of rain is .15, calculate expected profit for the car wash.
13. If you were asked to play a game in which you tossed a fair coin three times and
were given $2 for every head you threw, how much would you expect to win on
average?
P(Head on any toss) = 1 /2
So expected number of heads in 3 tosses = 3*1 /2 = 1 .5
Hence,
Winning amount = 1 .5*2 = $3
14. X has the following probability distribution P(X).
X 1 2 3 4
P(X) 0.1 0.5 0.2 0.2
Compute the variance value of X.
, 15 A total of 50 raffle tickets are sold for a contest to win a car. If you purchase one
ticket, what are your odds against winning?
Total number of Tickets=50
If we purchase one ticket ,then
P(winning a car)=P= 1 /50
pobability againist winning a car= 1 -P= (1 -1 /50)=49/50.
16. The mean of the binomial distribution is equal to. Np
