The average of a group of 20 numbers is 30 and that of another group of 30 numbers is 50. What is the average of all the numbers in both groups?

A43.5

B45

C40

D42 ✓ Correct

Correct answer: (D) 42

Explanation

The combined average is 42.

Sum of first group = 20 x 30 = 600.

Sum of second group = 30 x 50 = 1500.

Total sum = 600 + 1500 = 2100 over 20 + 30 = 50 numbers.

Combined average = 2100/50 = 42.

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