Question

45% of all 1st graders at Sierra Elementary School are female students. This year there are 54 female 1st graders at Sierra Elementary School. How many 1st graders are there at Sierra Elementary School this year?

Answer 1

number of first grader at Sierra elementary school = 120

Explanation:

The question says 45% of 1st graders at Sierra Elementary school are female student . This year there are 54 female 1st graders at Sierra Elementary school .The number of 1st graders at Sierra elementary school can be calculated below .

Let

the number of 1st grader = a

45 % of a = female population

This year the female 1st graders at the Sierra elementary school are 54. This can represented as follows

45% × a = 54

45/100 × a = 54

45a/100 = 54

cross multiply

45a = 5400

divide both sides by 45

a = 5400/45

a = 120

number of first grader = 120

Answer 2

There are 120 1st graders at Sierra Elementary School this year

Explanation:

Let n represent the total number of 1st graders at Sierra Elementary School

Since 45% of all 1st graders at Sierra Elementary School are female students and this year there are 54 female 1st graders, 45% of n is equal to 54

→ n(
`(45)/(100)`) = 54

→ 45n = 5400

→ n = 120