BdMO National Primary 2016/4

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samiul_samin
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BdMO National Primary 2016/4

Unread post by samiul_samin » Thu Feb 15, 2018 11:17 am

Jannat had some marbles and she gave half of these to Mahi.Then she divided rest of the marble in two groups so that one group had one more marble than the other group.She gave half of the marbles of the group that contains even number of marbles to Tasnina.Finally she had four marbles remaining.How many marbles she had at first?

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samiul_samin
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Re: BdMO National Primary 2016/4

Unread post by samiul_samin » Thu Feb 15, 2018 7:43 pm

Hint
odd+odd=even.Calculate backward.
Answer
$10$

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samiul_samin
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Re: BdMO National Primary 2016/4

Unread post by samiul_samin » Thu Feb 15, 2018 7:50 pm

Solution
At last she had $4$ marbels.It is not a sum of two even number. As it is an even number it is a sum of two odd numbers.
Now,$4=3+1$
She gave Tasnina $2/2=1$ marble.
She gave Mahi $2+3=5$ marbles.
So, at first,she had $5+5=10$ marbles.
Answer is $\fbox {10}$

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