Question

the average marks of the class of 100 students is 75. If the average marks of the students who passed the examination is 80 and the average marks of the students who failed in the examination is 30. Find the number of the students who passed the examination?

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

Answer 2

Answer:

Step-by-step explanation:

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