The average of marks obtained by 240 students in an exam is 70,if average of passed is 78 & failed is 30, wht?

Question

The average of marks obtained by 240 students in an exam is 70, if average of passed students is 78 & average of failed students is 30, what is the number of students who passed in the exam? - please fetch me the answer with working i.e., the way to solve this...

Answer 1

Let x be the number of students who passed the exam.

then we can write

240 x 70 = 78x + (240 - x) x 30

16800 = 78x + 7200 - 30x

16800 - 7200 = 78x - 30x

9600 = 48x

x = 200

So, 200 students passed the exam. I hope the working out is clear.

Answer 2

Let x be the number of students who passed the exam.
Then the following equation describes the data given to us.
240*70(total marks obtained by all the students)=x*78(total marks obtained by students who passed)+(240-x)*30(total marks of students who didn't pass)
And the answer comes out to be 200.
The number of students who passed the exam were 200.

Answer 3

Total marks = 240 * 70 = 16800
Let number of students who passed is "x" .

x * 78 + (240 - x ) * 30 = 16800

48 * x = 16800 - 7200 = 9600

x = 200

Number of students passed = 200
Students failed = 40

Answer 4

y = people passed
(78 x y + (240-y) x 30) divided by 240 = 70

Answer 5

n: total number of students x: total grade of all stdnts
y: number of passed z: tot. grade of passed
f: number of failed w: tot grade of failed,

x/n = 70, x/240 = 70, x=16800....................(1)
z/y = 78..............(2)
w/f = 30, f= n-y therefore w/(n-y) = 30.........(3)
we will find y so, we should have two equations which have y in them. These are the equations (2) and (3)

z= 78*y
w= 30n - 30y

by addition of these two,

z+w = 30n+48y, we already know that z+w = x so,

x= 30n + 48y
16800 = 30*240 + 48y
y=200

Answer 6

Do your own homework - there's no shortcut to learning and you haven't even shown us that you have tried