Amy wrote 320 pages (rounded to nearest tens) in 20 days (rounded to n

Question

Amy wrote 320 pages (rounded to nearest tens) in 20 days (rounded to nearest tens). On an average, the number of pages ‘x’ that Amy wrote per day must have been between -

A. 315/25≤x≤325/15
B. 315/15<x<325/25
C. 315/24≤x≤324/15
D. 320/25<x<320/15
E. 315/20<x<325/20

chetan2u · Answer

320 pages (rounded to nearest tens) - means 315 to 324
20 days (rounded to nearest tens) - means 15 to 24

Average is pages /days..
Max average will be (max pages)/(least days)= \frac{324}{15} 
Min average will be (min pages)/(max days)= \frac{315}{24}

The range, therefore, is  \frac{315}{24} ≤x≤ \frac{324}{15}

C

KarishmaB · Answer

For more on rounding rules, check: https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2014/0 ... or-a-five/

Fdambro294 · Answer

I just wanted to get a confirmation on the rounding rules used.

Generally, I understand that we are taught since grade school the following:

0, 1, 2, 3, 4 ——-> round down

And ——-> 6, 7, 8, 9 ——-> round up

However, I was under the impression that “5” is considered a controversial topic in the field of mathematics (not that I’m a scholar...I wish)

For instance: 325 ——-> rounded to the nearest Tens Digit

Some would say 330, others would say 320.

Any input would be much appreciated. Thank you.

Posted from my mobile device

ramlala · Answer

Hi Fdambro294 You are correct, For <5, result is down to ten.....and > 5 than up to ten. Here we are talking about number of pages i.e. integer . So <5 = 4 is down to ten......and > 5 is up to ten So if we say 320 (nearest ten) than it shall be any integer from 31 5 to 32 4 and for 20 (nearest ten) its from 1 5 to 2 4 I hope this may clear your query

chetan2u · Answer

Rounding off should mean ‘getting the integer to closest tens value.’
In that regard, 5 becomes a bit problematic as it is right in middle of the two tens. For example 25 is equidistant from 20 to 30.

Now, there are various rules floating around. One such says that get it to closest even number when divided by 10.
That is 15 moves to 20 and 25 also moves to 20.

But I am yet to see something of this kind on GMAT. GMAT would avoid anything that is controversial.

IanStewart · Answer

If you are asked "If you round 35 to the nearest ten, what do you get?" there is no unique good answer, because there is no one "nearest ten" to 35. Both 30 and 40 are equally close to 35. Sometimes schools teach some kind of rule that governs what to do in an ambiguous situation like this, but those rules are different in different countries. So the GMAT will never test how to round 35 to the nearest ten, because then the GMAT would only be testing where you learned math, and that's not what the GMAT is trying to measure. The GMAT is very careful to avoid using questions that might be culturally biased (that's one of the things they check for when they evaluate experimental questions), so they will never use a question that gives an advantage to test takers who happen to have studied in a national education system that teaches the same 'rounding rule' the GMAT happens to have arbitrarily settled on. So this issue will never matter on a genuine test question.

As for the question in this thread:

it makes no sense, either grammatically or mathematically. It is clearly an attempt to copy Q192 in OG2018 PS (the "Cindy drove her car..." question) with different numbers and nouns. If anyone wants to see a properly designed question testing these concepts, the OG question is the one to look at. This question, however, is logically nonsensical. For one thing, we don't know that the quantities must be measured in integers, and we'd need to know that to have any hope of justifying the "OA" of C. But worse still, if C is right, and x is between 315/24 and 324/15, then clearly A is also right, because every number that is between 315/24 and 324/15 is automatically also between 315/25 and 325/15, the range in A, because the range in A completely contains the range in C.

So this question doesn't make any sense, and there's no reason to study it.

Posted from my mobile device

Fdambro294 · Answer

Thank you for the responses. Much appreciated.

Posted from my mobile device

MagnusSamIBA · Answer

Amy wrote 320 pages (rounded to the nearest tens), so the actual pages written could be between 315 and 324. She did this in 20 days (rounded to the nearest tens), so the actual number of days could be between 15 and 24.

To find the range for the average number of pages per day, we divide the minimum and maximum possible pages by the maximum and minimum possible days, respectively.

Max average: 324 pages / 15 days = 324/15

Min average: 315 pages / 24 days = 315/24
----
the average number of pages written per day lies between 315/24 and 324/15.

Answer: C (315/24 ≤ x ≤ 324/15)

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Amy wrote 320 pages (rounded to nearest tens) in 20 days (rounded to n

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