The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member?
সমাধান
সঠিক উত্তর: Option C
Let the members be Old Having age O + other 9 having ages x and New one having age Y Sum of their ages = (Y + 9 × x) and average = (Y + 9 × x)/10 Before 4 years sum was (O + 9 x – 10 × 4) and average = (O + 9 x – 10 × 4) /10 equating, Y + 9 x = O + 9x – 40 Y = O – 40 Younger is 40 years younger than Old one.
