In: Statistics and Probability
Suppose a poll of 20 voters is taken in a large city. The purpose is to determine x, the number who favor a certain candidate for mayor. Suppose that 40% of all the city’s voters favor the candidate.
a. Find the mean and standard deviation of x.
b. What is the probability that x <=10.
c. Find the probability that x > 12.
d. Find the probability that x = 11
e. Graph the probability distribution of x.
Solution: We are given:
a. Find the mean and standard deviation of x.
Answer: The mean and standard deviation of x is:
b. What is the probability that x <=10.
Answer: We have to find:
c. Find the probability that x > 12.
Answer: We have to find:
d. Find the probability that x = 11
Answer: We have to find
e. Graph the probability distribution of x.
Answer: The probability distribution of x is given below:
x | P(x) |
0 | 0.00004 |
1 | 0.00049 |
2 | 0.00309 |
3 | 0.01235 |
4 | 0.03499 |
5 | 0.07465 |
6 | 0.12441 |
7 | 0.16588 |
8 | 0.17971 |
9 | 0.15974 |
10 | 0.11714 |
11 | 0.0710 |
12 | 0.03550 |
13 | 0.01456 |
14 | 0.00485 |
15 | 0.00129 |
16 | 0.00027 |
17 | 0.00004 |
18 | 0.00000 |
19 | 0.00000 |
20 | 0.00000 |
The graph of the probability distribution of x is: