Time Conversion

[guest612]

Questions asks:

[Deleted b/c question source is on banned list - old paper-and-pencil GMATs are banned!]

Correct Answer: D. 6:30.
Source: Source: TC 37 Section 4 #15 (Not ManhattanGMAT)

How so?

I can come close by doing the following but I'm still not completely there:

24hours * 60 minutes = 1,448.

2,880,717 minutes / 1,448 minutes is approximately 2000 with a remainder of 3. So I can guess it's a 3 minute difference from the current time of 6:27 which gives me either B. 6:24 or D. 6:30. However, I'm asking the following:
1) How do I know if it's B or D? Do I add or subtract 3?
2) Is the math even correct or did I get lucky?
3) Is there a better way to solve this? The math could get very tedious and I presume there's a better way to solve this if the have given this question on past exams.

Thank you!

[RonPurewal]

i don't know what 'tc' stands for, but it seems you should stop using that source. this problem is unbelievably inauthentic and un-gmat-like - just terrible.

in any case:

given the choices, all you have to look at is the last digit.
you're starting with a time that ends with a 7, and subtracting some other amount of time that ends with a 7. that means that the answer has to end with a zero.

done.

[guest612]

Hi Ron,

Thanks for the reply. The answer, however, is D which doesn't end in 7. I may just not care about this question as I agree that this question seems unlikely.

By TC I mean Test Code. It's from ETS. They were past exams before they went to CAT. I don't mind forgetting about this problem if it's highly unlikely to be on the exam and the exam has deviated from such type of questions since then.

However, if you think this is a bad source in general, please let me know.

Thanks!

[Guest]

You did the math right.

2880717/60 = 48011.95

so, we need to minus 48011.95 hours from 6:27

.95 hours = 95/100 * 60 = 57 minutes

So, 6:27 - XXX:57 = XXX:30

[guest612]

thanks! i guess it does get tedious but it works. thanks!

[RonPurewal]

Hi Ron,

Thanks for the reply. The answer, however, is D which doesn't end in 7.

go back and read that post again; the answer has to end with 7 - 7, or 0.

It's from ETS. They were past exams before they went to CAT. I don't mind forgetting about this problem if it's highly unlikely to be on the exam and the exam has deviated from such type of questions since then.

that's unreal; this problem seriously looks like a fake from one of those low-quality prep books. i'm nonplussed.

the other 'tc' questions you've posted haven't been as heinous as this one, so i'm not ready to tell you to 86 them. but, if you will, a question: have you already gone through all the og's (yellow og11, green quant supplement, purple verbal supplement) and the gmatprep tests?

[guest612]

ron, i swear it's from the test code! you can check! :)

i have gone through the more guide books but will go back through them since i've been focusing on the test codes recently. going to hit the green book now! thanks again.

[StaceyKoprince]

And the old paper-and-pencil tests are also on the banned list... (basically, anything that GMAC still sells it doesn't permit to be posted for free online). So, don't post those here.

And, also, don't study from them! They're WAY too old and not always representative of the current test. I do remember questions like this one back from my old paper-and-pencil days but things like this don't show up anymore. (Thankfully! :)