This question was previously asked in

MP Police SI Official Paper 5(Held on : 28 Oct 2017 Shift 2)

Option 2 : 16

पर्यायवाची

11201

15 Questions
15 Marks
12 Mins

Given:

Total numbers = 10

By mistake, the student wrote 26 instead of 36

The incorrect average = 15.

Concepts used:

Average = (Sum of all observations)/(Number of observations)

Calculation:

Sum of all observations = 10 × 15 = 150

Correct sum of observations = Incorrect sum + Correct number - Incorrect number

⇒ 150 + 36 – 26 = 160

Correct average =160/10 = 16

∴ The correct average is 16.

__Shortcut Trick__

By mistake sum of all numbers decreased by (36 - 26) = 10

So, average of 10 numbers decreased by 10/10 = 1

If it was not taken wrongly then the average should be 15 + 1 = 16.

∴ The correct average is 16.