Question

90 students average marks 50 passed students average 70 and failed student average 50 how many failed students are

Answer 1

Let the number of passed students be x
then number of failed students will be 100 -x
A/q
total marks of 100 students = 100×75 = 7500
total marks of passed students = 80x
total marks of failed students = 30(100 -x) = 3000 - 30x
now,
(3000 - 30x) + 80x = 7500
⇒50x= 4500
⇒x =90
number of students passed is 90