Question

In an Aerobic class, the average age of all the members was 54.5 years, 11 members left the class and 7 new members joined. If the average age increased by 3 years and the total age decreased by 140, what was the number of members in the class initially?

A 30 Correct Answer Incorrect Answer
B 36 Correct Answer Incorrect Answer
C 32 Correct Answer Incorrect Answer
D 40 Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

Let the original member be x Total age of these members = 54.5x Total age of (x – 4) members = (54.5x  – 140) years According to the question,  54.5x  – 140 = (x  – 4) `xx` 57.5 ⇒ 54.5x  – 140 = 57.5x  – 230  ⇒ 57.5x  – 54.5x  = 230 – 140 ⇒ 3x = 90  x = 30

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