The mean of 20 items is 55. If two items 45 and 30 are removed, the new mean of the remaining items is :

Answer: Option C

According to the question,
Mean of 20 items is = 55
Sum of 20 items is
= 55 × 20 = 1100
Two items removed
= 45 + 30 = 75
Now, sum of 18 items
= 1100 - 75
= 1025
∴ Average = $$\frac{1025}{18}$$ = 56.9