Answer :
The mean is x amount of numbers added together divided by x. Since both mean questions have only 2 numbers, you times 40 and 35 by 2 to reverse the question.
40 X 2 = 80 = a + b.
35 X 2 = 70 = b + c.
100 = a + b + c
80 and 70 are quite close together. Therefore, b would probably be around 40 - 60. I used trial and error to work out the answer.
b = 40
80 - 40 = 40.
a = 40.
70 - 40 = 30.
c = 30.
40 + 40 + 30 = 110.
THIS ANSWER IS WRONG.
b = 50.
80 - 50 = 30.
a = 30.
70 - 50 = 20.
c = 20.
50 + 30 + 20 = 100.
THIS ANSWER IS CORRECT.
a = 30
b = 50
c = 20
40 X 2 = 80 = a + b.
35 X 2 = 70 = b + c.
100 = a + b + c
80 and 70 are quite close together. Therefore, b would probably be around 40 - 60. I used trial and error to work out the answer.
b = 40
80 - 40 = 40.
a = 40.
70 - 40 = 30.
c = 30.
40 + 40 + 30 = 110.
THIS ANSWER IS WRONG.
b = 50.
80 - 50 = 30.
a = 30.
70 - 50 = 20.
c = 20.
50 + 30 + 20 = 100.
THIS ANSWER IS CORRECT.
a = 30
b = 50
c = 20
Mean of A & B : (A+B)/2 = 40. Cross multiply
A + B = 80.
Mean of B & C: (B+C)/2 = 35. Cross multiply
B + C = 70.
(A + B + C) = 100 Note A + B = 80.
Therefore C = 100 - (A+B) = 100 - 80 = 20.
C = 20.
A = 100 - (B+C) = 100 - 70 = 30.
A = 30.
A + B = 80
30 + B = 80
B = 80 -30 = 50.
A = 30, B = 50, C = 20.
A + B = 80.
Mean of B & C: (B+C)/2 = 35. Cross multiply
B + C = 70.
(A + B + C) = 100 Note A + B = 80.
Therefore C = 100 - (A+B) = 100 - 80 = 20.
C = 20.
A = 100 - (B+C) = 100 - 70 = 30.
A = 30.
A + B = 80
30 + B = 80
B = 80 -30 = 50.
A = 30, B = 50, C = 20.