Hello,
Can you please assist with this:
If three glasses contain 1/6 liter, 1/8 liter, and 1/9 liter of water, respectively,
then the total amount of water in the three glasses is between...
(A) 0 and 1/3 liters
(B) 1/3 and 1/2 liters
(C) 1/2 and 2/3 liters
(D) 2/3 and 5/6 liters
(E) 5/6 and 1 liters
OA: B
I tried to solve as follows:
1/6 + 1/8 + 1/9
= (12 + 9 + 8)/72
= 29/72
However, I was not sure how to proceed further. Can you please assist?
Thanks,
Sri
To find the total amount of water in 3 glasses
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Hi Sri,
You arrived till 29/72
72*4 = 288 <290
so 29/72 should be approximate .4
Come to options now,
A = 0-0.33
Not in our eliminate
B = 0.33-0.5
Yes
Hence Ans is B
Regards,
Uva.
You arrived till 29/72
72*4 = 288 <290
so 29/72 should be approximate .4
Come to options now,
A = 0-0.33
Not in our eliminate
B = 0.33-0.5
Yes
Hence Ans is B
Regards,
Uva.
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Hi!gmattesttaker2 wrote:Hello,
Can you please assist with this:
If three glasses contain 1/6 liter, 1/8 liter, and 1/9 liter of water, respectively,
then the total amount of water in the three glasses is between...
(A) 0 and 1/3 liters
(B) 1/3 and 1/2 liters
(C) 1/2 and 2/3 liters
(D) 2/3 and 5/6 liters
(E) 5/6 and 1 liters
OA: B
I tried to solve as follows:
1/6 + 1/8 + 1/9
= (12 + 9 + 8)/72
= 29/72
However, I was not sure how to proceed further. Can you please assist?
Thanks,
Sri
Uva did a great job saying what you could do next, so I want to discuss what you could have done instead - everyone taking the GMAT should strive to follow the Lazy Test-taker Rule: Do the least amount of work possible to answer each question.
On questions that ask you to find a range, focusing on limits is often a huge time saver. Such is the case on this question.
If our 3 fractions had all been 1/6, the sum would be 3/6 = 1/2
If our 3 fractions had all been 1/9, the sum would be 3/9 = 1/3
Since our 3 fractions are between 1/6 and 1/9 (inclusive), the answer must be between 1/3 and 1/2 - choose (B)!
Note that it's not a coincidence that things worked out so nicely - the GMAT wants to reward you for strategic thinking, so many questions are designed to be quickly solvable with logic and common sense.
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If all 3 glasses each contained 1/9 liter, then the total volume = 3(1/9) = 1/3 liter.gmattesttaker2 wrote:Hello,
Can you please assist with this:
If three glasses contain 1/6 liter, 1/8 liter, and 1/9 liter of water, respectively,
then the total amount of water in the three glasses is between...
(A) 0 and 1/3 liters
(B) 1/3 and 1/2 liters
(C) 1/2 and 2/3 liters
(D) 2/3 and 5/6 liters
(E) 5/6 and 1 liters
OA: B
Since 2 of the glasses each contain MORE than 1/9 liter, the ACTUAL total volume must be GREATER than 1/3 liter.
If all 3 glasses each contained 1/6 liter, then the total volume = 3(1/6) = 1/2 liter.
Since 2 of the glasses each contain LESS than 1/6 liter, the ACTUAL total volume must be LESS than 1/2 liter.
Thus, the actual total volume must be BETWEEN 1/3 and 1/2 liter.
The correct answer is B.
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I'd typically solve this question using the same approach used by Mitch and Stuart, but here's another approach that wouldn't take long.gmattesttaker2 wrote: If three glasses contain 1/6 liter, 1/8 liter, and 1/9 liter of water, respectively,
then the total amount of water in the three glasses is between...
(A) 0 and 1/3 liters
(B) 1/3 and 1/2 liters
(C) 1/2 and 2/3 liters
(D) 2/3 and 5/6 liters
(E) 5/6 and 1 liters
All students should know the following conversions from fraction to decimal:
1/2 = 0.5
1/3 ≈ 0.33
1/4 = 0.25
1/5 = 0.2
1/6 ≈ 0.17
1/7 ≈ 0.14
1/8 = 0.125
1/9 ≈ 0.11
So, 1/6 + 1/8 + 1/9 ≈ 0.17 + 0.125 + 0.11
From here, we can "eyeball" this sum to see that we get approximately 0.4, so the answer must be B
Cheers,
Brent
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Brent@GMATPrepNow wrote:I'd typically solve this question using the same approach used by Mitch and Stuart, but here's another approach that wouldn't take long.gmattesttaker2 wrote: If three glasses contain 1/6 liter, 1/8 liter, and 1/9 liter of water, respectively,
then the total amount of water in the three glasses is between...
(A) 0 and 1/3 liters
(B) 1/3 and 1/2 liters
(C) 1/2 and 2/3 liters
(D) 2/3 and 5/6 liters
(E) 5/6 and 1 liters
All students should know the following conversions from fraction to decimal:
1/2 = 0.5
1/3 ≈ 0.33
1/4 = 0.25
1/5 = 0.2
1/6 ≈ 0.17
1/7 ≈ 0.14
1/8 = 0.125
1/9 ≈ 0.11
Hi Brent ,
I just want to add that these fractions can be memorised quickly if you know percentage - fraction equivalent .... this is what is mean ...
100/2 = 50 and 1/2 = .5
100/3 = 33.33 so 1/3 = .33
100/4 = 25 so 1/4 = .25
and if one wants to remember 1/7 = then 7 x 2 =14 and 14 x 2 = 28
therefore 1/7 = .1428.....
else 100/7 ... 7x14 + 2 ... therefore 1/7 = .14
similarly 1/8 , 1/9 .... etc
one need not memorise anything ....
if u know 1/3 then 2/3 can be calculated easily like this ...
since 1/3 = .33 so 2/3 = .33x2 = .66
and for 5/6 since 1/6 = .1666 so 5/6 = .1666x5 = .833...
this way one can convert also the option choice into decimals and the figurue given in question into decimal too and see what the answer is ...
though not a preferable method as this is time consuming ... just an alternate method to solve question.