Chapter No 6
Multiple Choice Quiz
1 A random variable is a function or rule that assigns a numerical value to each outcome in the sample space of a stochastic experiment.
A) True
B) False
2) The birth weight of a newborn baby is an example of a discrete random variable.
A) True
B) False
3To describe the possible outcomes and their probabilities when you roll one fair die, we would use a discrete binomial distribution.
A) True
B) False
4For the Poisson distribution to apply, the events must occur randomly and independently over a continuum of time or space.
A) True
B) False
5When π = 0.70 the binomial distribution is positively skewed.
A) True
B) False
6A discrete probability distribution
A) assigns a probability to each value of the random variable.
B) can assume any value between 1 and +1.
C) is appropriate when the probability of success is an integer.
7Which statement is incorrect?
A) The Poisson distribution is always skewed right.
B) The binomial distribution may be skewed left or right.
C) The uniform distribution is never skewed.
D) The Bernoulli distribution has two equally likely outcomes.
8Historically, 2% of the stray dogs in the city of Southfield are unlicensed. On a randomlychosen day, the Southfield city animal control officer picks up 7 stray dogs. What is the probability that at least one will be unlicensed?
A) .8681
B) .1319
C) .3670
D) .1240
9In a randomlychosen week, which probability model would you use to describe the number of accidents at the intersection of two streets?
A) Uniform.
B) Binomial.
C) Poisson.
D) Geometric.
10Which probability model would you use to describe the number of damaged printers in a random sample of 12 printers taken from a shipment of 70 printers that contains 6 damaged printers?
A) Poisson.
B) Hypergeometric.
C) Binomial.
D) Geometric.
11Consider the following probability distribution of the random variable X:
X 
P (X) 
100 
.10 
150 
.20 
200 
.30 
250 
.30 
300 
.10 

1.00 
The expected value of X is:
A) 175
B) 150
C) 200
D) 205
12A carnival has a game of chance: a fair coin is tossed. If it lands heads you win $1.00 and if it lands tails you lose $0.50. How much should a ticket to play this game cost if the carnival wants to break even?
A) $.25
B) $.50
C) $.75
D) $1.00
13A random variable X is distributed binomially with n = 8 and π = 0.70. The standard deviation of the variable X is approximately
A) 0.458
B) 2.828
C) 1.680
D) 1.296
14In Quebec , 90 percent of the population subscribes to the Roman Catholic religion. In a random sample of 8 Quebecois find the probability that the sample contains at least five Roman Catholics.
A) .0050
B) .0331
C) .9950
D) .9619
15On average, a major earthquake (Richter scale 6.0 or above) occurs 3 times a decade in a certain California county. Find the probability that at least one major earthquake will occur within the next decade.
A) .9810
B) .0498
C) .1994
D) .9502
16If the probability of success is .25, what is the probability of obtaining the first success within the first 3 trials?
A) .4218
B) .5781
C) .1406