Math Problem Statement

In a statistics class of 39 students, there were 10 men and 29 women. Three of the men and four of the women received an A in the course. A student is chosen at random from the class. (a) Find the probability that the student is a woman. (b) Find the probability that the student received an A. (c) Find the probability that the student is a woman or received an A. (d) Find the probability that the student did not receive an A.

Solution

Let’s solve each part of this problem step-by-step.

Given Information:

  • Total students = 39
  • Men = 10, Women = 29
  • Students who received an A: 3 men and 4 women

Solution:

(a) Probability that the student is a woman

The probability P(Woman)P(\text{Woman}) is calculated by dividing the number of women by the total number of students.

P(Woman)=Number of WomenTotal Students=2939P(\text{Woman}) = \frac{\text{Number of Women}}{\text{Total Students}} = \frac{29}{39}

Calculating this value:

P(Woman)0.7436P(\text{Woman}) \approx 0.7436

(b) Probability that the student received an A

The probability P(Received an A)P(\text{Received an A}) is calculated by dividing the total number of students who received an A by the total number of students.

Total students who received an A = 3 (men) + 4 (women) = 7

P(Received an A)=739P(\text{Received an A}) = \frac{7}{39}

Calculating this value:

P(Received an A)0.1795P(\text{Received an A}) \approx 0.1795

(c) Probability that the student is a woman or received an A

To find P(Woman or Received an A)P(\text{Woman or Received an A}), we use the formula for the union of two events:

P(Woman or Received an A)=P(Woman)+P(Received an A)P(Woman and Received an A)P(\text{Woman or Received an A}) = P(\text{Woman}) + P(\text{Received an A}) - P(\text{Woman and Received an A})

From above:

  • P(Woman)=0.7436P(\text{Woman}) = 0.7436
  • P(Received an A)=0.1795P(\text{Received an A}) = 0.1795

Now, P(Woman and Received an A)P(\text{Woman and Received an A}) is the probability that a student is a woman and received an A, which is calculated by dividing the number of women who received an A by the total number of students.

P(Woman and Received an A)=4390.1026P(\text{Woman and Received an A}) = \frac{4}{39} \approx 0.1026

Substituting these values:

P(Woman or Received an A)=0.7436+0.17950.10260.8205P(\text{Woman or Received an A}) = 0.7436 + 0.1795 - 0.1026 \approx 0.8205

(d) Probability that the student did not receive an A

The probability P(Did not receive an A)P(\text{Did not receive an A}) is the complement of the probability of receiving an A.

P(Did not receive an A)=1P(Received an A)P(\text{Did not receive an A}) = 1 - P(\text{Received an A})

From (b), we know P(Received an A)0.1795P(\text{Received an A}) \approx 0.1795, so:

P(Did not receive an A)=10.1795=0.8205P(\text{Did not receive an A}) = 1 - 0.1795 = 0.8205

Summary of Answers:

  1. (a) Probability that the student is a woman: 0.7436\approx 0.7436
  2. (b) Probability that the student received an A: 0.1795\approx 0.1795
  3. (c) Probability that the student is a woman or received an A: 0.8205\approx 0.8205
  4. (d) Probability that the student did not receive an A: 0.8205\approx 0.8205

Would you like a detailed explanation of any step or have any questions?


Related Questions

  1. What is the probability that a student chosen is a man?
  2. What is the probability that the student is a man and received an A?
  3. How would the probability change if there were 5 women who received an A?
  4. What is the probability that a randomly chosen student is a woman who did not receive an A?
  5. How would you calculate the probability if there was a different total number of students?

Tip

Always verify if events are mutually exclusive or independent, as this affects which probability rules to apply.

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Math Problem Analysis

Mathematical Concepts

Probability
Basic Statistics

Formulas

P(Event) = Number of favorable outcomes / Total number of outcomes
P(A or B) = P(A) + P(B) - P(A and B)
P(A') = 1 - P(A)

Theorems

Probability of Union of Two Events
Complement Rule

Suitable Grade Level

Grades 10-12