Find how much younger is the new member ?
The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member.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 ?
Let the sum of nine member (total) =x
and the age of old one=z
so its average 4 yrs before=(x+z)/10.
after 4 yrs let z be replaced by y.
so now avg=(x+4*10+y)/10
now (x+z)/10=(x+40+y)/10
so after solving it found
z=y+40.
so old person is 40yrs older than young one.
I would make one small adjustment to your answer. When you add 40, you’re adding the four years the retired old person aged. That shouldn’t enter into your calculation, since that person is no longer in the group. Therefore the equation should be
(x+z)/10 = (x+36+y)/10
which yields a difference of 36 years. You can test this with an arbitrary set of numbers to see that it is correct.
Agreed!
Your Answer
More puzzles to try-
Weak defeat the strong and then defeat themselves riddle
How can the weak defeat the strong, but at a later date, defeat themselves. How is it possible?Read More »Kris Cross
Can you place six X (crosses) in below board without making three in a row in any way ?Read More »How could this be?
Samuel was out for a walk and it started to rain. He did not have an umbrella and he wasn’t ...Read More »Seconds in a year
How many seconds are there in one year?Read More »C O W
How do you spell COW in thirteen letters?Read More »Who are the married couples?
Serge, Chris et Marc are married to Lise, Monique and Lily. Hints : 1) Serge loves golf but hates boating. 2) ...Read More »Why the second man died?
Two men went into a restaurant. They sat at a table and the waiter came by and asked, “What do ...Read More »Wine Glass Stem
Why Wine Glass Stem is so long?Read More »Word does not belong with the others
Which word does NOT belong with the others? A. index B. glossary C. chapter D. bookRead More »Barnyard Bonanza
Hidden in each of the sentences below is the name of an animal that can be found in a barnyard. ...Read More »Group of three riddle
There is a group of three. One is sitting down, and will never get up. The second eats as much ...Read More »Two hands with good face riddle
He have two hands with good face, but he can not scratch himself. Name him ?Read More »Parrot repeats everything it hears puzzle
A pet shop owner had a parrot with a sign on its cage that said “Parrot repeats everything it hears.” ...Read More »How far is Morocco riddle
If it is 1,800 kilometres to America, 1,200 kilometres to Japan, 2,400 kilometres to New Zealand, and 1,400 kilometres to ...Read More »Measure exactly 4 cups of sugar
You are in a cookie factory, and need to make a huge batch of chocolate chip cookies. The recipe calls ...Read More »Josephus problem – Sword Killing and Survival Puzzle
100 people are standing in a circle in an order of 1 to 100. No.1 has a sword he kills ...Read More »A true IAS Aspirant
How can a man go eight days without sleep?Read More »Jail and Hospital visit
There is a brother and a sister. The boy wants to visit his father in jail, and the sister wants ...Read More »Lion’s Den
A man walked into a room, and there were three doors. The first door had a sign which read “Lion’s ...Read More »Love More Than Life
What does man love more than life, hate more than death or mortal strife; That which contented men desire; the ...Read More »