Question

At the beginning of the school year, the 7th grade class at Oak Hill Middle School has 480 students. There are 270 girls and 210 boys.

part 1:
What is the probability that a randomly selected 7th grade student is a girl?
part 2:
Nineteen of the girls and 22 of the boys moved away, while 13 new girls and 20 new boys enrolled in the 7th grade at Oak Hill. After these changes in the class' composition, what is the probability that a randomly selected 7th grade student is a boy?

Answer 1

The probability of selecting a girl from the 7th grade class is 0.5625. After changes in the class composition, the probability of selecting a boy is 0.4407.

Step-by-step explanation:

Part 1: To find the probability that a randomly selected 7th grade student is a girl, we need to divide the number of girls by the total number of students. In this case, there are 270 girls in a class of 480 students. So the probability of selecting a girl is:

P(girl) = Number of girls / Total number of students = 270 / 480 = 0.5625

Part 2: After the changes in the class' composition, we need to recalculate the probability of a randomly selected student being a boy. First, we need to find the new number of boys. The initial number of boys was 210. After 22 boys moved away and 20 new boys enrolled, there are now 210 - 22 + 20 = 208 boys. The new total number of students is 480 - 19 + 13 - 22 + 20 = 472. So the probability of selecting a boy is:

P(boy) = Number of boys / Total number of students = 208 / 472 = 0.4407

Answer 2

Part 1: 43.75%

Part 2: 44.07%

Step-by-step explanation:

Hello!

(Pt.1) First, set up a ratio
`210/480`. Next, you use long division I got the percent 43.75. After that, you subtract 6 from the girls group, (because of them moving away and then more coming back.) and 2 from the boys group. Then, you subtract those from the school "population" and you get 472 as the final population. So then you set up another ratio,
`208/472`. I got a percent of 44.07% from that.

Thanks For Reading!