SOLUTION: Dhruv bought some white sugar and some brown sugar. He used an equal amount of white and brown sugar. He had 3/5 of the while sugar and 1/2 of the brown sugar left. What fraction o

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Dhruv bought some white sugar and some brown sugar. He used an equal amount of white and brown sugar. He had 3/5 of the while sugar and 1/2 of the brown sugar left. What fraction o      Log On


   



Question 1202921: Dhruv bought some white sugar and some brown sugar. He used an equal amount of white and brown sugar. He had 3/5 of the while sugar and 1/2 of the brown sugar left. What fraction of the sugar which Dhruv bought was used?
(1) 4/7
(2) 4/9
(3) 5/11
(4) 7/10

Found 4 solutions by ikleyn, math_tutor2020, MathTherapy, greenestamps:
Answer by ikleyn(52931) About Me  (Show Source):
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.
Dhruv bought some white sugar and some brown sugar.
He used an equal amount of white and brown sugar.
He had 3/5 of the while sugar and 1/2 of the brown sugar left.
What fraction of the sugar which Dhruv bought was used?
(1) 4/7
(2) 4/9
(3) 5/11
(4) 7/10
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Let  "w"  be the amount of the white sugar Dhruv bought.

Let  "b"  be the amount of the brown sugar Dhruv bought.


He used  %282%2F5%29w  and  %281%2F2%29b.


From the problem, we have this equation

    %282%2F5%29%2Aw = %281%2F2%29%2Ab    ("He used an equal amount of white and brown sugar"),

or  0.4*w = 0.5*b.                         (1)


They want you calculate this ratio  

    %280.4%2Aw+%2B+0.5%2Ab%29%2F%28w%2Bb%29.                       (2)


From (1), express  w = %280.5%2F0.4%29%2Ab = 1.25*b  and substitute it into (2).  You will get

   %280.4%2Aw+%2B+0.5%2Ab%29%2F%28w%2Bb%29 = %280.4%2A1.25b+%2B+0.5%2Ab%29%2F%281.25b%2Bb%29 = %280.5b%2B0.5b%29%2F%282.25b%29 = b%2F%282.25b%29 = 1%2F2.25 = 1%2F%28%289%2F4%29%29 = 4%2F9.


ANSWER.  The fraction of the sugar Dhruv used was  4%2F9  of the total amount of the sugar.

Solved.



Answer by math_tutor2020(3817) About Me  (Show Source):
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Answer: 4/9

Explanation:

He has 3/5 of the white sugar left over, so 2/5 of it was used.
He also used up 1/2 of the brown sugar.

Normally when it comes to fractions we try to get the denominators to be the same (often the LCD).
In this rare case, I'll make the numerators equal to a common multiple.
I'll go with 2 as this common numerator.
2/5 stays the same
1/2 becomes 2/4

Dhruv used 2/5 of the white sugar and 2/4 of the brown sugar.
The reason I made the numerators the same was because he used an equal amount of sugar from each type.
So that's why I want those '2's to match up.

He used up 2+2 = 4 parts of sugar out of 5+4 = 9 parts total.
Therefore we arrive at 4/9 to represent the fractional amount of sugar used.

Answer by MathTherapy(10558) About Me  (Show Source):
You can put this solution on YOUR website!
Dhruv bought some white sugar and some brown sugar. He used an equal amount of white and brown sugar. He had 3/5 of the while sugar and 1/2 of the brown sugar left. What fraction of the sugar which Dhruv bought was used?

(1) 4/7

(2) 4/9

(3) 5/11

(4) 7/10

Let amount of white and brown bought, be W and B, respectively
As 3%2F5 of white (W) remained, he used 2%2F5 of the white (W), or 2W%2F5
As 1%2F2 of brown (B) remained, he used 1%2F2 of the brown (B), or B%2F2
Since the same amount of white and brown was used, then we get: matrix%281%2C3%2C+2W%2F5%2C+%22=%22%2C+B%2F2%29
                                                                 5B = 4W ------ Cross-multiplying 
                                                                 matrix%281%2C3%2C+B%2C+%22=%22%2C+4W%2F5%29
Total amount used: 
 Total amount bought:  
  Fraction of total amount bought thatw's used: 

Answer by greenestamps(13216) About Me  (Show Source):
You can put this solution on YOUR website!


Let W = amount of white sugar he bought
let B = amount of brown sugar he bought

He had 3/5 of the white sugar left, so he used 2/5 of it; he had 1/2 of the brown sugar left, so he used 1/2 of it.

He used equal amounts of white and brown sugar:

(2/5)W = (1/2)B
.4W = .5B

Use that to find the ratio of white sugar to brown sugar:

W/B = .5/.4 = 5/4
W:B = 5:4

Having that ratio...
let 5x be the amount of white sugar he bought
let 4x be the amount of brown sugar he bought

The total amount of sugar he bought was 5x+4x = 9x.

He used 2/5 of the white sugar: (2/5)(5x) = 2x;
He used 1/2 of the brown sugar: (1/2)(4x) = 2x.

The total he used was 2x+2x = 4x.

The fraction of the sugar that he used was (4x)/(9x) = 4/9.

ANSWER: 4/9