Question

The average marks of the three students L, M and N is 80. Another man P enters the group of these three and makes the average 75. Now, a man Q whose marks 6 more than P, replaces M and average of the L, N, P and Q becomes 70. What is the marks of M?

• A. 80
• B. 90
• C. 86
• D. 72

Answer 1

The Correct Option is C

The correct option is (C): 86.
L + M + N = 80*3 ___(i)
L + M + N + P = 75*4 ___(ii)
Solving (i) and (ii), we get
80*3 + P = 75*4
P = 300 - 240 = 60
Q = 6 + P = 66
L + N + P + Q = 70*4 ___(iii)
Putting the value of P and Q, we get
L + N + 60 + 66 = 280
L + N = 280 - 126 = 154
Now, putting the value of L and N in equation (i), we get
154 + M = 80*3
M = 240 - 154 = 86.