Hy guys plz answer this question with explanation
Five years ago , the average age of p and q was 15 years, average age of p, q and r today is 20 years, how old will r be after 10 years.
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[QUOTE=sahilkhokhar;1025984]Five years ago , the average age of p and q was 15 years, average age of p, q and r today is 20 years, how old will r be after 10 years.[/QUOTE]
5 years ago, average age of p & q was: (We are subtracting 5 as it was 5 years ago & dividing by 2 as it was their average age.) {(p-5)+(q-5)}/ 2 = 15 (p+q-10)/2 = 15 Multiply by 2 on both sides p+q-10 = 30 p+q= 30+10 p+q= 40 -------- Equation (I) Average age of p,q & r today: (Dividing by 3 as it is average age of 3) (p+q+r)/3 = 20 Multiply by 3 on both sides p+q+r = 60 ------ Equation (II) Now subtract equation I from equation 2 p+q+r = 60 - p+q = 40 ------------- r = 20 ------------- present age of r= 20 years age of r after 10 years= 20+10 age of r after 10 years= 30 years |
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