The mean of 25 observations was calculated to be 44. Later on it was found that two of the observations 34 and 46 were wrongly copied as 28 and 42. The correct mean will be :

1. 39.4

2. 40.4

3. 44.4

4. 43.9

Given

Wrong mean = 44

Total observations = 25

So,

Total wrong sum = 25 × 44 = 1100

Two numbers were wrongly copied:

Wrong numbers → 28 and 42

Correct numbers → 34 and 46

⇒ 34 - 28 = 6

⇒ 46 - 42 = 4

⇒ Increased sum = 6 + 4 = 10

So, the correct sum = 1100 + 10 = 1110

∴ Correct mean = $\dfrac{1110}{25}$ = 44.4

Hence, option 3 is the correct option.