We know the width of the rectangle in the middle of the trapezoid is 24 (from the top of the image), so we can subtract that from the bottom width of the trapezoid to get the combined length of the bottom of both triangles.
Since this is an isosceles trapezoid, both triangle bases are the same length, so we can cut this value in half to get the length of and
Finally, we can use the Pythagorean Theorem to find the length of :
First case:
average of test score =70
number of students =p
total score of 'p' students = ( average of test score)*( number of students)
total score of 'p' students =70p
Second case:
average of test score =92
number of students =n
total score of 'n' students = ( average of test score)*( number of students)
total score of 'n' students =92n
total number of students = p+n
total average score =86
so, total score =86(p+n)
total score = total score of 'p' students +total score of 'n' students
now, we can simplify it
now, we can find p/n
................Answer