In: Statistics and Probability
In a survey of 177 people, the following data were obtained relating gender to color-blindness:
Color-Blind (C) | Not Color - Blind | Total | |
Male (M) | 92 | 36 | 128 |
Female (F) | 33 | 16 | 49 |
Total | 125 | 52 | 177 |
A person is randomly selected. What is the probability that the
person is:
a) Male?
b) Male and Color-blind?
c) Male given that the person is Color-blind?
d) Color-blind given that the person is Male?
e) Female given that the person is not
Color-blind?
f) Are the events Male and Color blind
independent? Enter yes or no.
Total number of people = 177
a)
Number of male = 128
Probability that the person is Male = (Number of male
Total number of people) = (128
177) = 0.7232
Answer: 0.7232
b)
Number of Male and Color-blind = 92
Probability that the person is Male and Color-blind = (Number of
Male and Color-blind
Total number of people)
Probability that the person is Male and Color-blind = (92
177) = 0.5198
Answer: 0.5198
c)
Number of Male and Color-blind = 92
Number of Color-blind = 125
Probability that the person is Male given that the person is
Color-blind = (Number of Male and
Color-blind
Number of Color-blind)
Probability that the person is Male given that the person is
Color-blind = (92
125) = 0.736
Answer: 0.736
d)
Number of Male and Color-blind = 92
Number of Male = 128
Probability that the person is Color-blind given that the person
is Male = (Number of Male and
Color-blind
Number of Male)
Probability that the person is Color-blind given that the person
is Male = (92
128) = 0.7187
Answer: 0.7187
e)
Number of Female and not Color-blind = 16
Number of Not Color-blind = 52
Probability that the person is Female given that the person is
not Color-blind = (Number of Female and not Color-blind
Number of Not Color-blind )
Probability that the person is Female given that the person is
not Color-blind = (16
52) = 0.3077
Answer: 0.3077
f)
If the events Male and Color blind are independent then probability that the person is Male and Color-blind will be equal to the product of probability that the person is Male and probability that the person is Color-blind
We write the above statement in equation form for understanding
If probability that the person is Male and Color-blind =
(probability that the person is Male
probability that the person is Color-blind) then events Male and
Color blind are independent
we know the values of probability from above question except probability that the person is Color-blind
probability that the person is Color-blind = (Number of
Color-blind
Total number of people) =(125
177) =0.7062
(probability that the person is Male
probability that the person is Color-blind) = 0.7232
0.7062 = 0.5107
So, probability that the person is Male and Color-blind
(probability that the person is Male
probability that the person is Color-blind)
Therefore, events Male and Color blind are not independent
Answer : no.