The numbers 24, 45, a, 35, 59, 83, 46, b, 29, 74 are serially numbered as they appear in the sequence. When each number is added to its serial number, then the average of the new numbers formed is 55. The average of the missing numbers (a and b) is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 50
Numbers are given as 24, 45, a, 35, 59, 83, 46, b, 29 & 74.
When a serial number is added to them, the sum will be,
⇒ 24 + 1 + 45 + 2 + a + 3 + 35 + 4 + 59 + 5 + 83 + 6 + 46 + 7 + b + 8 + 29 + 9 + 74 + 10
⇒ 450 + a + b
Which is equivalent to 55 × 10 = 550
⇒ a + b = 100
Average = 100 / 2 = 50