Question

66. The average of the marks of 8 students is 30, that of the first two is 22/2 and of the next three is 24, the marks of the sixth student is 3 less than the seventh and less by 9 than the eighth student. What was the marks obtained by the eighth student ?
(A) 42
(B) 48
(C) 46
(D) 44

Answer 1

Answer:

The mark of eight student be x

The mark of sixth student = x-9

The mark of seventh student= x-6

Average of all three x-5

Now the total average has to be equal 30

22 + 72+3x -15= 30×8

79+ 3x= 240

        x=48

Answer 2

Answer:

x = 48

Explanation:

The mark of the eight student be x

The mark of the sixth student = x-9

The mark of the seventh student = x - 6

Average of all three = x - 5

Now the total average has to be equal 30

22 + 72 + 3x - 15 = 30 × 8

79 + 3x = 240

x = 48