Problema Solution
Parks Elementary School has an enrollment of 640 students, all of whom are in the first through sixth grades. twenty-five percent of the students are in the first or second grade. Thirty percent of the students are in the third or fourth grade. There are forty more sixth graders than fifth graders.
How many fifth graders attend the school?
How many sixth graders attend the school
Answer provided by our tutors
Hi,
All students -------> 640
students in 1st and 2d grade -----> 25% of 640
students in 3rd and 4th grade ----> 30% of 640
then the percentage of students that are in 1st second Third or fourth grade is (25+30)% = 55%
hence the percentage of the rest ( the remaining stedents that are in fifth or sixth grade) is (100 - 55)% = 45%
then the number of students that are in fifth or sixth grade is 45% of 640 = 45*640/100 = 288 students
Let m be the number of students that are in the fifth grad and n the number of students in sixth grad.
we have n+m = 288 ( equation 1)
and we know that n = m + 40 ( equation 2)
we sibstitute n in the first equation we obtain: m+40 + m = 288 then 2m = 288 - 40 = 248
then m = 248/2 = 124
the number of fifth graders that attend the school is 124
equation 1 ==> n + 124 = 288 ==> n = 288 - 124 = 164
the number of sixth graders that attend the school is 164