Mean of 10 numbers is 30. Later on it was observed that numbers 15, 23 are wrongly taken as 51, 32. The correct mean is :

Answer: Option A

According to the question,
Mean of 10 numbers is = 30
∴ Sum of 10 numbers is = 300
It was observed that numbers 15, 23 are wrongly taken as 51, 32
Difference
= (51 + 32) - (15 + 23)
= 83 - 38
= 45 (more)
∴ Actual sum of 10 numbers
= 300 - 45 = 255
∴ Actual average of 10 numbers
= $$\frac{255}{10}$$ = 25.5