The average age of 4 staff members is 30. When a fifth member joins, the average becomes 32. How old is the new member?
Correct answer: D. 40 years old
The total age of the first four is 4 × 30 = 120. The new total is 5 × 32 = 160. The new member is 160 − 120 = 40 years old.
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