Reading 9: Common Probability Distributions - LOS d, (Part

答案和详解如下：

1、The number of days a particular stock increases in a given five-day period is uniformly distributed between zero and five inclusive. In a given five-day trading week, what is the probability that the stock will increase exactly three days?

A)   0.333.

B)   0.200.

C)   0.167.

D)   0.600.

The correct answer was C)    

If the possible outcomes are X0,1,2,3,4,5), then the probability of each of the six outcomes is 1/6=0.167.

2、Which of the following random variables would be most likely to follow a discrete uniform distribution?

A)   The outcome of the roll of two standard, six-sided dice where X is the sum of the numbers facing up.

B)   The number of heads on the flip of two coins.

C)   The number of red coats to yellow coats on the floor of the NYSE.

D)   The outcome of a roll of a standard, six-sided die where X equals the number facing up on the die.

The correct answer was D)

The discrete uniform distribution is characterized by an equal probability for each outcome. A single die roll is an often-used example of a uniform distribution. In combining two random variables, such as coin flip or die roll outcomes, the sum will not be uniformly distributed. The number of red coats to yellow coats is a ratio that is not likely uniformly distributed.