Average Practice Test 5

Sum of marks in the 1st, 2nd, 3rd and 4th examinations = (59 × 4) = 236 …(1)
Sum of marks in the 2nd, 3rd 4th and 5th examinations = 61 × 4 = 246 …(2)
Subtracting (1) from (2) we get:
Marks of the 5th examination - Marks of 1st examination = 10
Let the marks of first and fifth examination be 8x and 9x respectively.
Then,
9x - 8x = 10
x = 10
∴ Marks of fifth examination = 9x = 9 × 10 = 90