A Simple Problem of Cherries

Algebra Level 2

Swarna has a bag of cherries, and eats 1 2 \frac { 1 }{ 2 } of them, then passes the rest to Madhur, who eats 1 3 \frac { 1 }{ 3 } of the remainder. The bag is then passed to Bala, who eats 1 4 \frac { 1 }{ 4 } of the remaining cherries.

There are 6 cherries left. How many were there originally?


The answer is 24.

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5 solutions

Kaelyn Willingham
Jun 26, 2014

Let c c be the number of cherries in the bag. If Swarna eats half of the cherries, then the remainder is c 1 2 c c-\frac { 1 }{ 2 } c . If Madhur eats 1 3 \frac { 1 }{ 3 } of that, then the remainder is ( c 1 2 c ) 1 3 ( c 1 2 c ) \left( c-\frac { 1 }{ 2 } c \right) -\frac { 1 }{ 3 } \left( c-\frac { 1 }{ 2 } c \right) . If Bala eats 1 4 \frac{ 1 }{ 4 } of THAT, then the remainder is [ ( c 1 2 c ) 1 3 ( c 1 2 c ) ] 1 4 [ ( c 1 2 c ) 1 3 ( c 1 2 c ) ] \left[ \left( c-\frac { 1 }{ 2 } c \right) -\frac { 1 }{ 3 } \left( c-\frac { 1 }{ 2 } c \right) \right] -\frac { 1 }{ 4 } \left[ \left( c-\frac { 1 }{ 2 } c \right) -\frac { 1 }{ 3 } \left( c-\frac { 1 }{ 2 } c \right) \right] .

Since there are 6 cherries remaining, it can be said that [ ( c 1 2 c ) 1 3 ( c 1 2 c ) ] 1 4 [ ( c 1 2 c ) 1 3 ( c 1 2 c ) ] = 6 \left[ \left( c-\frac { 1 }{ 2 } c \right) -\frac { 1 }{ 3 } \left( c-\frac { 1 }{ 2 } c \right) \right] -\frac { 1 }{ 4 } \left[ \left( c-\frac { 1 }{ 2 } c \right) -\frac { 1 }{ 3 } \left( c-\frac { 1 }{ 2 } c \right) \right]=6 , which when simplified gives c = 24 c=24 .

Lots of algebra!

Madhur Agrawal
Feb 10, 2018

I ate only 4 cherries out of 24? Impossible!

Let x x be the original number of cherries. Swarna eats 1 2 \dfrac{1}{2} of them, so the remainder is x 1 2 x = 1 2 x x-\dfrac{1}{2}x=\dfrac{1}{2}x . Madhur eats 1 3 \dfrac{1}{3} of the remainder, so the remainder is 1 2 x 1 3 ( 1 2 x ) = 1 3 x \dfrac{1}{2}x-\dfrac{1}{3}\left(\dfrac{1}{2}x\right)=\dfrac{1}{3}x . Bala eats 1 4 \dfrac{1}{4} of the remaining cherries and 6 6 cherries were left. So, 1 3 x 1 4 ( 1 3 x ) = 1 4 x = 6 \dfrac{1}{3}x-\dfrac{1}{4}\left(\dfrac{1}{3}x\right)=\dfrac{1}{4}x=6 . Hence, x = 4 × 6 = 24 x=4\times 6 =\boxed{24}

Sunil Pradhan
Jul 13, 2014

assume number initially be 12, (LCM of 2, 3, 4)

Swarna ate 12/2 = 6 then remaining = 6

Madhur ate 6/3 = 2 remaining = 4

Bala ate 4/4 = 1 remaining = 3

when 3 cherries remaining, initially it was 12

so when 6 cherries remaining, initially it was 12/3 × 6 = 24

6 ÷ 3 4 ÷ 2 3 ÷ 1 2 = 24 6\div \frac { 3 }{ 4 } \div \frac { 2 }{ 3 } \div \frac { 1 }{ 2 } =\boxed{24}

If 6 cherries are left after eating 1/4, that means 24 were there originally. If 24 cherries were left after eating 1/3, that means that there were 72 originally. If 72 cherries were left after eating 1/2, then initially there must have been 144 cherries. Why are we saying that there were only 24 cherries originally?

Tarun Khanna - 6 years, 11 months ago

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Only 1/4 were eaten, meaning that 6 cherries is 3/4 of what was there before 1/4 was eaten.

A Former Brilliant Member - 6 years, 11 months ago

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