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By: JessicaTan (offline)  Friday, March 15 2013 @ 05:10 AM CDT (Read 1201 times)  
JessicaTan

Please help. (apologise, no answer key)


5) Mary & Lucy have some jellybeans each. If Mary gives Lucy 24 jellybeans, they will have an equal number of jellybeans. If Mary gives Lucy 56 jellybeans, Mary will have 1/3 as many jellybeans as Lucy. How many jellybeans does Mary have at first?


rdgs

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By: echeewh (offline)  Friday, March 15 2013 @ 07:51 PM CDT  
echeewh

Hey Jessica,

This is very much of a model drawing method that will help solve the problem.

Following is my worked solution:

<After1>

M |------------|
L |------------|

Working backwards,
L: -24; M: +24

<Before>

M |--------------|<-24->|
L |------|<-24->

Translating the above, M has 48 more jellybeans than L at first.

<process>
M: -56; L: +56

<After2>

**<-1u-> < - 8 - 48 >
M |------|<--------------
L |--------|<-- 8 + 48 -->|
******* <-- 8 + 8 + 48 ->
**<--------- 3u ------------>

hence, 2u --> 8 + 8 + 48 = 64
1u --> 32

M (at first) = 1u + 56 --> 32 + 56 = 88

==========

Trust this helps.

Do let me know again if this is different from your Answerkey or if there's further clarification.

Cheers,
Edward

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Registered: 04/21/11
Posts: 625

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By: JessicaTan (offline)  Saturday, March 16 2013 @ 02:10 AM CDT  
JessicaTan

Quote by: echeewh

Hey Jessica,

This is very much of a model drawing method that will help solve the problem.

Following is my worked solution:

<After1>

M |------------|
L |------------|

Working backwards,
L: -24; M: +24

<Before>

M |--------------|<-24->|
L |------|<-24->

Translating the above, M has 48 more jellybeans than L at first.

<process>
M: -56; L: +56

<After2>

**<-1u-> < - 8 - 48 >
M |------|<--------------
L |--------|<-- 8 + 48 -->|
******* <-- 8 + 8 + 48 ->
**<--------- 3u ------------>

hence, 2u --> 8 + 8 + 48 = 64 (Kindly explain how did you get 2u?)
1u --> 32

M (at first) = 1u + 56 --> 32 + 56 = 88

==========

Trust this helps.

Do let me know again if this is different from your Answerkey or if there's further clarification.

Cheers,
Edward

Forum Regular Member
Regular Member

Registered: 10/17/09
Posts: 82

Profile Email    
   
By: echeewh (offline)  Saturday, March 16 2013 @ 07:33 PM CDT  
echeewh

Hi Jessica,

Hopefully the following explanation will help you further.

We were given that "Mary will have 1/3 as many jellybeans as Lucy."

Hence, the '2u' is the 'how much more does L have than M after the transfer'.

Following is the translation in mathematical form.

<Before>

M = 1p + 48; L = 1p

After M gave 56 to L, ...

<After2>

M = 1p + 48 - 56 = 1p - 8
L = 1p + 56

Given that after the transfer, M = 1u while L = 3u, we have ...

M: 1u --> 1p - 8
L: 3u --> 1p + 56

So, L - M: 3u - 1u --> 56 + 8
2u --> 64

=============

Trust you find the above useful.

Regards,
Edward

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Registered: 04/21/11
Posts: 625

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