SOLUTION: Ben wanted to know how old his friend Mr. Stone was. Mr. Stone told him, "I started school when I was 4-1/2 year old, and I stayed at the same school for 1/6 of my life. I was in

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: Ben wanted to know how old his friend Mr. Stone was. Mr. Stone told him, "I started school when I was 4-1/2 year old, and I stayed at the same school for 1/6 of my life. I was in      Log On

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Question 23887: Ben wanted to know how old his friend Mr. Stone was. Mr. Stone told him, "I started school when I was 4-1/2 year old, and I stayed at the same school for 1/6 of my life. I was in the army 1/5 of my life and when I left the army I spent 1/4 of my life as a clerk. Now I have spent 1/3 of my life in retirement." How old is Mr. Stone?
Answer by Sridi(6) About Me  (Show Source):
You can put this solution on YOUR website!
For such problems, use a variable for the age. Call it x.
Currently Mr. Stone is x yrs old.
He was 4.5 yrs old when he started school.---- 4.5
For 1/6 of his life , he was in school ------ %281%2F6%29+x
in the army 1/5 of my life -------- %281%2F5%29+x
1/4 of my life as a clerk ---------- %281%2F4%29+x+
spent 1/3 of my life in retirement ----- %281%2F3%29+x
That was his life to date. whatever he has done in life thus far must = his age.
x = +4.5+%2B+%28x%2F6%29+%2B+%28x%2F5%29+%2B+%28x%2F4%29+%2B+%28x%2F3%29+
Now this is a fraction simplification problem.
The LCD for 6, 5, 4 and 3 is 60
therefore %28x%2F6%29+%2B+%28x%2F5%29+%2B+%28x%2F4%29+%2B+%28x%2F3%29+
is now written as
%2810x+%2B+12x+%2B+15x+%2B+20x%29%2F60%29+which+is+equal+to++57x%2F60+
Plug this back in the first equation
x = 4.5+%2B+57x%2F60
Subtract 57x/60 from both sides.
+x+-+%2857x%2F60%29+=+4.5+
3x%2F60+=+4.5+
+x%2F20+=+4.5
x+=+20+%2A+4.5
x = 90 years.