sandipgumtya wrote:Hi Mitch,
The method I followed took me nearly 4 min.Can u pl suggest a quicker method or make it easier to understand?
Sandip.
An alternate approach is to PLUG IN THE ANSWERS, which represent the number of blueberries in each blue box.
Answer choice D: 50 blueberries per box
If Danny disposed of one blue box for one additional red box, the total number of berries (of both kinds) would increase by 25.
In other words, subtracting one box of 50 blueberries and adding in one box of S strawberries is equal to an increase of 25:
-50 + S = 25
S = 75 strawberries per box.
If Danny disposed of one blue box for one additional red box, the difference between the total number of strawberries and the total number of blueberries would increase by 95.
Let Danny start with 2 boxes of strawberries and 2 boxes of blueberries.
Original difference = (total strawberries) - (total blueberries) = (75+75) - (50+50) = 50.
After one box of blueberries is exchanged for one box of strawberries, new difference = (75+75+75) - 50 = 175.
(new difference) - (original difference) = 175-50 = 125.
The increase in the difference is too great.
Eliminate D.
Answer choice B: 40 blueberries per box
If Danny disposed of one blue box for one additional red box, the total number of berries (of both kinds) would increase by 25.
In other words, subtracting one box of 40 blueberries and adding in one box of S strawberries is equal to an increase of 25:
-40 + S = 25
S = 65 strawberries per box.
If Danny disposed of one blue box for one additional red box, the difference between the total number of strawberries and the total number of blueberries would increase by 95.
Let Danny start with 2 boxes of strawberries and 2 boxes of blueberries.
Original difference = (total strawberries) - (total blueberries) = (65+65) - (40+40) = 50.
After one box of blueberries is exchanged for one box of strawberries, new difference = (65+65+65) - 40 = 155.
(new difference) - (original difference) = 155-50 = 105.
The increase in the difference is still too great.
Eliminate B.
Notice the pattern:
In D, (new difference) - (original difference) = 125.
In B, (new difference) - (original difference) = 105.
The smaller the answer choice, the smaller the value of (new difference) - (original difference).
Implication:
To yield (new difference) - (original difference) = 95, the correct answer must be SMALLER than answer choice B.
The correct answer is
A.
Answer choice A: 35 blueberries per box
If Danny disposed of one blue box for one additional red box, the total number of berries (of both kinds) would increase by 25.
In other words, subtracting one box of 35 blueberries and adding in one box of S strawberries is equal to an increase of 25:
-35 + S = 25
S = 60 strawberries per box.
If Danny disposed of one blue box for one additional red box, the difference between the total number of strawberries and the total number of blueberries would increase by 95.
Let Danny start with 2 boxes of strawberries and 2 boxes of blueberries.
Original difference = (total strawberries) - (total blueberries) = (60+60) - (35+35) = 50.
After one box of blueberries is exchanged for one box of strawberries, new difference = (60+60+60) - 35 = 145.
(new difference) - (original difference) = 145-50 = 95.
Success!
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