Question

there are four numbers.if we leave out any one number the average of the remaining three number will be 45

Answer 1

If the four numbers are A, B, C and D, then we know that

A + B + C = 45 × 3

A + B + D = 60 × 3

A + C + D = 65 × 3

B + C + D = 70 × 3

Now add them up to get 3A + 3B + 3C + 3D = (45 + 60 + 65 + 70) × 3

Which is A + B + C + D = (45 + 60 + 65 + 70) = 240. So their average is 240/4 = 60

Answer 2

Answer:

60

Step-by-step explanation:

If the four numbers are A, B, C and D, then we know that

A + B + C = 45 × 3

A + B + D = 60 × 3

A + C + D = 65 × 3

B + C + D = 70 × 3

Now add them up to get 3A + 3B + 3C + 3D = (45 + 60 + 65 + 70) × 3

Which is A + B + C + D = (45 + 60 + 65 + 70) = 240. So their average is 240/4 = 60