Question

Your teacher is choosing 2 students to run an errand for her. There are 12 girls and 10 boys in the class. What is the probability that both the students chosen to run the errand will be girls? (Put your answer in simplified fraction form)

Answer 1

2 / 7

Explanation:

There are 22 students in total so the chance of being picked is of 12 /22

But when one girl is chose the number of girls decrease so it will be 11/22, so you multiply 12 / 22 x 11 / 22 = 132 / 462

The missing thing is simplify it, so in simplify number the answer will be 2 / 7

Answer 2

2/7

Explanation:

There are 22 (12 + 10) total students in the class. That means that the chance of the first student picked being a girl is 12/22.

Now, we must calculate the chance of the next student to be picked also being a girl - however, there is a trap here! Remember that since a girl has been picked, the total student pool has decreased to 21 and and the total number of girls has decreased to 11. This means the new chance of girl being picked is 11/21.

To find the probability of both these events happening in conjunction, these fractions must be multiplied. 12/22 * 11/21 = 132/462, which simplifies to 2/7.