A student is selected at random from a class of 40 students, where 25 are boys a
Practice Questions
Q1
A student is selected at random from a class of 40 students, where 25 are boys and 15 are girls. What is the probability that the student is a girl given that the student is not a boy?
1/3
1/2
2/3
3/4
Questions & Step-by-Step Solutions
A student is selected at random from a class of 40 students, where 25 are boys and 15 are girls. What is the probability that the student is a girl given that the student is not a boy?
Correct Answer: 1
Step 1: Identify the total number of students in the class, which is 40.
Step 2: Determine how many of those students are boys, which is 25.
Step 3: Calculate the number of students that are not boys. Since there are 40 students and 25 are boys, the number of students that are not boys is 40 - 25 = 15.
Step 4: Recognize that the students who are not boys are all girls, which means there are 15 girls.
Step 5: To find the probability of selecting a girl given that the student is not a boy, use the formula: Probability = (Number of girls) / (Number of students that are not boys).
Step 6: Substitute the numbers into the formula: Probability = 15 / 15.
Step 7: Simplify the fraction: 15 / 15 = 1.
Conditional Probability – The probability of an event occurring given that another event has already occurred.
Total Probability – Understanding the total number of outcomes in a probability scenario.
