In a class of 30 students, 18 are girls. If a student is chosen at random, what

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Question: In a class of 30 students, 18 are girls. If a student is chosen at random, what is the probability that the student is a boy?

Options:

Correct Answer: 1/3

Solution:

The number of boys is 30 - 18 = 12. The probability is 12/30 = 2/5.

In a class of 30 students, 18 are girls. If a student is chosen at random, what is the probability that the student is a boy?

In a class of 30 students, 18 are girls. If a student is chosen at random, what is the probability that the student is a boy?

Correct Answer: 2/5

Step 1: Identify the total number of students in the class. There are 30 students.
Step 2: Identify the number of girls in the class. There are 18 girls.
Step 3: Calculate the number of boys by subtracting the number of girls from the total number of students: 30 - 18 = 12 boys.
Step 4: Write the probability formula for choosing a boy: Probability = (Number of boys) / (Total number of students).
Step 5: Substitute the numbers into the formula: Probability = 12 / 30.
Step 6: Simplify the fraction 12 / 30 to its lowest terms: 12 / 30 = 2 / 5.

Probability Calculation – Understanding how to calculate the probability of an event by dividing the number of favorable outcomes by the total number of outcomes.
Complementary Counting – Using the total number of students and the number of girls to find the number of boys, demonstrating the concept of complementary counting.