Guess The Age

Algebra Level 2

Four years ago the average age of A and B was 18 years. Average age of A, B, C today is 24 years. After 8 years, the age of C will be?


The answer is 36.

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3 solutions

Four years ago the average age of A and B was ( A 4 ) + ( B 4 ) 2 = 18 \color{#D61F06}{\dfrac{(A-4)+(B-4)}{2}=18} .Simplifying this we get A + B = 44 \color{#3D99F6}{A+B=44} .The average age of A,B and C today is A + B + C 3 = 24 \color{#20A900}{\dfrac{A+B+C}{3}=24} .Substituting the value of A + B = 44 \color{#69047E}{A+B=44} and simplifying,we get C = 28 \color{rubinered}{C=28} .So the age of C 8 years from now will be 28 + 8 = 36 \color{#624F41}{28+8=\boxed{36}}

Shivam Gupta
Oct 6, 2014

well suppose the present ages of A, B and C be x, y and z respectively; now 4 years back the age of A and B will be x-4 and y-4 respectively; now according to the riddle find the average of their ages and put them equal to 18; {(x-4)+(y-4)}/2 =18) from here u will get x+y= 44; going through the question again we can calculate the age of C by following expression: (x+y+z)/3 = 24 and putting the value of (x+y) in the expression we will get the present age of C that is 28 and after 8 years C will be 36 years old

queries are always welcomed :)

Shivam Gupta - 6 years, 8 months ago

Four years ago: A + B = 36 A+B=36

Today: 36 + 8 + C = 72 36+8+C=72 \implies C = 28 C=28

Eight years from now: C + 8 = 28 + 8 = C+8=28+8= 36 \large{\color{#D61F06}\boxed{36}}

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