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By: awonder (offline)  Wednesday, May 04 2016 @ 09:37 AM CDT (Read 2211 times)  
awonder

Hi, need help on the this question. TIA.

Michael has some blue and white marbles in his bag. If he adds 10 white marbles, 60% of his marbles are blue. If he adds 45 blue marbles, 75% of his marbles are blue. How many marbles does he have in his bag?

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By: echeewh (offline)  Thursday, May 05 2016 @ 12:27 AM CDT  
echeewh

Hey <awonder>,

Following is my worked solution:

<1st IF>
<after 10W added>
B : W
60 : 40
3 : 2

<before>
B: 3u
W: 2u - 10

<2nd IF>
<after 45B added>

B: 3u + 45 --- (1)
W: 2u - 10 --- (2)

Given that 75% of his marbles are blue (B ), we have ...

B : W
75 : 25
3 : 1 --- (3)

From (1),(2),(3), we have ...

3u + 45 = 3 × (2u - 10)
3u + 45 = 6u - 30
6u - 3u --> 45 + 30
3u --> 75
1u --> 25

Hence <before> it has ...
B + W = 3u + 2u - 10 = 5u - 10
5u - 10 --> (5 × 25) - 10 = 115

======

Trust this helps.

Do let me know again if this is different from the <anskey> or if there's further clarification.

Cheers,
Edward

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By: awonder (offline)  Thursday, May 05 2016 @ 05:11 AM CDT  
awonder


Hi Edward, thanks a lot for the solution. May I know usually what shd we look out for first or how to figure out the concept for this kind of question? Hope u understand my question.


Quote by: echeewh

Hey <awonder>,

Following is my worked solution:

<1st IF>
<after 10W added>
B : W
60 : 40
3 : 2

<before>
B: 3u
W: 2u - 10

<2nd IF>
<after 45B added>

B: 3u + 45 --- (1)
W: 2u - 10 --- (2)

Given that 75% of his marbles are blue (B ), we have ...

B : W
75 : 25
3 : 1 --- (3)

From (1),(2),(3), we have ...

3u + 45 = 3 × (2u - 10)
3u + 45 = 6u - 30
6u - 3u --> 45 + 30
3u --> 75
1u --> 25

Hence <before> it has ...
B + W = 3u + 2u - 10 = 5u - 10
5u - 10 --> (5 × 25) - 10 = 115

======

Trust this helps.

Do let me know again if this is different from the <anskey> or if there's further clarification.

Cheers,
Edward

Forum Newbie
Newbie

Registered: 10/11/12
Posts: 4

Profile Email    
   


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