The average marks which marks of a class are 70. If the average marks of fail student are 40 and pass students is 80 marks . Find % of pass students ?
Answers
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
The % of pass students is 75%.
Given:
Average marks of a class = 70
Average marks of failed students = 40
Average marks of failed students = 80
To find:
% of pass students
Solution:
Let the number of total students be x and number of passed students be y,
Failed students = total students - passed students
= x-y
Average = total marks / total students
Total marks of passed students = average * number of passed students
= 80 * y = 80y
Total number of failed students = average of failed students * number of failed students = 40 * (x-y) = 40(x-y)
Total marks of class = total marks of passed students + total marks of failed students
= 80y + 40(x-y) = 80y + 40x - 40y
= 40 y + 40 x
Average of class = Total marks / total students
70 = (40x + 40y)/x
70x = 40x + 40y
70x - 40x = 40y
30x = 40y
Dividing both sides by 10,
3x = 4y
y/x = 3/4
% of pass students = (Total number of pass students/total number of students) * 100
= y/x * 100
= 3/4 * 100
= 300/4
= 75%
So, the % of pass students is 75%.
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