Seven Eleven

[thapliyalabhi]

Source-->Manhattan GMAT question bank

DS question:
Is y greater than 7/11 ?

(1) 1/5 < y < 11/12

(2) 2/9 < y < 8/13

OA-B

Solution given does not show any calculation. Solution only mentions both 2/9 and 8/13 are less than 7/11, 11/12 is greater than 7/11 etc.

My doubt:-Is there an easy way where we don't have to calculate decimal value of fractions(11/12,2/9,7/11,8/13) to answer questions like these. That would be really helpful in case of questions where values are bigger such as 247/321 etc.

[tim]

This sounds more like a question than a doubt. I say this because there are a surprising number of students on this forum who use this phrase, and it might get you into trouble in the business world one day. I understand that saying you have a doubt about something is perfectly acceptable in the dialect of English spoken in India (and maybe elsewhere), but in a more international context, the phrase sounds confrontational and even hostile, like you're questioning the integrity of whomever you're "doubting".

Anyway, on to your question. You definitely don't need to (and shouldn't) convert these fractions to decimals. What you should do instead is multiply both fractions by both denominators and compare the resulting integers. As an example, is 8/13 less than 7/11? Let's try it out:

8/13 compared to 7/11
8/13*13*11 compared to 7/11*13*11
8*11 compared to 7*13
88 compared to 91

Since 88 is less than 91, 8/13 is less than 7/11

[thapliyalabhi]

This sounds more like a question than a doubt. I say this because there are a surprising number of students on this forum who use this phrase, and it might get you into trouble in the business world one day. I understand that saying you have a doubt about something is perfectly acceptable in the dialect of English spoken in India (and maybe elsewhere), but in a more international context, the phrase sounds confrontational and even hostile, like you're questioning the integrity of whomever you're "doubting".

Anyway, on to your question. You definitely don't need to (and shouldn't) convert these fractions to decimals. What you should do instead is multiply both fractions by both denominators and compare the resulting integers. As an example, is 8/13 less than 7/11? Let's try it out:

8/13 compared to 7/11
8/13*13*11 compared to 7/11*13*11
8*11 compared to 7*13
88 compared to 91

Since 88 is less than 91, 8/13 is less than 7/11

Thanks Tim.
And I agree with you that my question was not a doubt. Will pay close attention to the difference in the future.

[tim]

Glad I could help!