Conditional Probability Worksheet

**Page 1**

1.

The frequency table shows the results from a poll conducted about reading the newspaper in the morning.

Use the data to find P (Reads Newspaper | child)

Adult | Child | |

Reads | 35 | 17 |

Does not read | 12 | 23 |

Use the data to find P (Reads Newspaper | child)

a. | $\frac{15}{40}$ | ||

b. | $\frac{17}{40}$ | ||

c. | $\frac{23}{40}$ | ||

d. | $\frac{12}{47}$ |

Among them, 17 read the newspaper in the morning.

So, P (Reads newspaper | Child) =

Correct answer : (2)

2.

The frequency table shows the results from a poll conducted about reading the newspaper in the morning.

Use the data to find P (Does not read Newspaper | Adult).

Adult | Child | |

Reads | 35 | 17 |

Does not read | 12 | 23 |

Use the data to find P (Does not read Newspaper | Adult).

a. | $\frac{12}{17}$ | ||

b. | $\frac{12}{87}$ | ||

c. | $\frac{12}{40}$ | ||

d. | $\frac{12}{47}$ |

Among them, 12 do not read newspaper in the morning.

So, P (does not read newspaper | Adult) =

Correct answer : (4)

3.

The table shows the population information of the percentage of male and female population in the U.S., in the year 2000, according to a census.

Using the table find:P (Male | Under 18).

Under 18 | Over 18 | |

Male | 26.8 | 73.2 |

Female | 24.6 | 75.4 |

Using the table find:P (Male | Under 18).

a. | 2.2% | ||

b. | 26.8% | ||

c. | 18.03% | ||

d. | 52.1% |

The probability that a person under 18 will be male is 52.1%.

Correct answer : (4)

4.

A math teacher gave her class two tests. 76% of the class passed the first test. 58% of the class passed both tests. Find the probability that a student who passed the second test, given that he passed the first test.

a. | 1.31 | ||

b. | 0.58 | ||

c. | 1.00 | ||

d. | 0.76 |

[Use P (B | A) =

=

Correct answer : (4)

5.

The table shows the population information of the percentage of male and female population in the U.S., in the year 2000, according to a census.

Under 18
## Solution:P (Female | over 18) == 0.507 The probability that a person over 18 is female is 50.7%. Correct answer : (0) 6.
The frequency table shows the school enrolment (in thousands) in the year 2000. Let C represents california.
Use the table to find P(C).
## Solution:The probability that a person enrolled in a school belongs to California = P(C)P (C) = = P (C) = 82.04% Correct answer : (2) 7.
The frequency table shows the school enrolment (in thousands) in the year 2000.
Let E represents elementary school.
Use the table to find P(E).
## Solution:P (E) = the probability that a person is enrolled in elementary school of California or New Jersey.P (E) = P (E) = 64.11% Correct answer : (4) 8.
The frequency table shows the school enrolment (in thousands) in the year 2000.
Let C represents california and G represents graduate school.
Use the table to find P(C and G).
## Solution:P (C and G) =The probability that a person enrolled in a graduate school of California is 20.7% Correct answer : (1) 9.
The frequency table shows the school enrolment (in thousands) in the year 2000.
Let N represents New Jersey and R represents Pre primary school.
Use the table to find P(R | N).
## Solution:P(R and N) =P(N) = P(R | N) = [Use P(R | N) = The probability that a person enrolls in primary school, given that the person is from New Jersey is 13.9%. Correct answer : (2) 10.
The frequency table shows the school enrolment (in thousands) in the year 2000.
Let C represents California and G represents graduate school.
Use the table to find the probability that a person is from California, given that he is in graduate school.
## Solution:The required probability can be described by the notation P(C | G).P (C | G) = [Use P (B | A) = P (C and G) = P (G) = P (C | G) = The probability that a person is from California given that he is in graduate school is 84.5%. Correct answer : (3) |