In year x, it rained on 40% of all Mondays and 20% of all Tuesdays. On what percentage of all the weekdays in year x did it NOT rain?
(1) During year x, it rained on 10% of all Wednesdays.
(2) During year x, it did not rain on 70% of Thursdays and it did not rain on 95% of all Fridays.
Reasoning Percent DS Question
This topic has expert replies
-
- Newbie | Next Rank: 10 Posts
- Posts: 7
- Joined: Mon Apr 08, 2013 3:51 pm
-
- Master | Next Rank: 500 Posts
- Posts: 423
- Joined: Fri Jun 11, 2010 7:59 am
- Location: Seattle, WA
- Thanked: 86 times
- Followed by:2 members
IMO E
St1: Rains 10% of all Wednesdays. but we dont know about Thursday and Fridays rain %. hence Insufficient
St2: Did not rain 70% Thursday and did not rain 95% of all fridays. dont know about wednesdays hence insufficient
St1 and St2 together: we dont know how many # of mondays, Tues, Wed, Thu and Fri are we looking at. A year has 365 days which is 52 weeks + 1 day (in case of leap year 2 days). dont know what this extra day is which is why i would say its INSUFFICIENT to answer.
Hence E
St1: Rains 10% of all Wednesdays. but we dont know about Thursday and Fridays rain %. hence Insufficient
St2: Did not rain 70% Thursday and did not rain 95% of all fridays. dont know about wednesdays hence insufficient
St1 and St2 together: we dont know how many # of mondays, Tues, Wed, Thu and Fri are we looking at. A year has 365 days which is 52 weeks + 1 day (in case of leap year 2 days). dont know what this extra day is which is why i would say its INSUFFICIENT to answer.
Hence E
GMAT/MBA Expert
- Anju@Gurome
- GMAT Instructor
- Posts: 511
- Joined: Wed Aug 11, 2010 9:47 am
- Location: Delhi, India
- Thanked: 344 times
- Followed by:86 members
Clearly none of the statements are individually sufficient.championspunch wrote:In year x, it rained on 40% of all Mondays and 20% of all Tuesdays. On what percentage of all the weekdays in year x did it NOT rain?
(1) During year x, it rained on 10% of all Wednesdays.
(2) During year x, it did not rain on 70% of Thursdays and it did not rain on 95% of all Fridays.
1 & 2 Together: Now we know on what percentage of each weekdays it did rain or did not rain. However, we do not know how how many weekdays are there in year X. Hence, we cannot answer the question.
This is because, there are either 365 or 366 days in the year X.
If there are 365 days in the year X : Dividing 365 days by 7, we get 52 weeks and 1 extra day. This one extra day may be a weekday or a Saturday/Sunday. Hence, the required percentage will change depending upon whether it is weekday or not and even if it is weekday, which weekday it is. Same is the case with 366 days.
Not sufficient
The correct answer is E.
Anju Agarwal
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Here's a little challenge question on the side:championspunch wrote:In year x, it rained on 40% of all Mondays and 20% of all Tuesdays. On what percentage of all the weekdays in year x did it NOT rain?
(1) During year x, it rained on 10% of all Wednesdays.
(2) During year x, it did not rain on 70% of Thursdays and it did not rain on 95% of all Fridays.
The above question could never be an official GMAT question. Why not?
Cheers,
Brent
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
I have to head out for the day, so here's the reason.Brent@GMATPrepNow wrote:
Here's a little challenge question on the side:
The above question could never be an official GMAT question. Why not?
Cheers,
Brent
In any given year, there will be either 52 or 53 Mondays, Tuesdays, etc.
So, it's impossible to say that it rained on 40% of all Mondays or 20% of all Tuesdays, etc.
For example, if there are 52 Mondays, then 40% of 52 = 20.8, which means that it rained on 20.8 days (impossible).
Cheers,
Brent