Question

Which of the following variables follow binomial distribution? I. 5% drivers in Winnipeg drive under the influence of alcohol on Saturdays. 20 drivers are stopped randomly and are asked to take alcohol test. X = number of drivers who test positive for alcohol. II. Two bags, A and B contain marbles. Bag A contains 40 red, 30 blue and 30 yellow marbles. Bag B contains 20 red, 10 blue and 20 yellow marbles. A marble is selected from each bag. X = number of red marbles. III. Two bags, A and B contain marbles. Bag A contains 40 red, 30 blue and 30 yellow marbles. Bag B contains 20 red, 10 blue and 20 yellow marbles. A marble is selected from each bag. X = number of blue marbles.

Select one:

a. I and II only.

b. I. only

c. Only III.

d. II AND III only

e. All I, II and III.

Answer 1

Conditions for binomial distribution:

1) number of trails n are fixed in advance.

2) probability of success P is fixed &same for each trial

3) there are only two possible outcomes of each trial I.e success & failure

4) each trial is independent of other.

## Answer:

I] n=20& P= 0.05 &all the conditions are satisfied

II] Number of trials n is not fixed. This is not binomial

III] number of trials n is not fixed. This is not binomial

option b is correct

b) I only