To receive a driver license, sixteen year-olds at Culliver High School have to pass both a written and a practical driving test. Everyone has to take the tests, and no one failed both tests. If 30% of the 16 year-olds who passed the written test did not pass the practical, how many sixteen year-olds at Culliver High School received their driver license?
(1) There are 188 sixteen year-olds at Culliver High School.
(2) 20% of the sixteen year-olds who passed the practical test failed the written test.
why is B not the correct answer. I read the explanation but i just don't understand this question.
Please help
GMAT Forum
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- cooper2248817
- JK
Have you drawn out the value boxes to do Pass Driving, No Pass Driving / Pass Writing, No Pass Writing
I will do the problem and get back to you tomorrow if you do not understand it after doing the chart.
Actually...for Stacey...I will do it now.
PDriving No PDriving Total
Pass Writing .7x .3x x
No Pass Writing 0
Total .3x
You want to know what .7x is - so what is x could be a rephrasing
1) You know there are 188 sixteen year olds. That does not give us x, that gives us the total students so INSUFFICIENT (Hi stacey)
PDriving No PDriving Total
Pass Writing .7x .3x x
No Pass Writing 0
Total .3x 188
2) You now 20% of the people that passed the practical driving, failed the written. We are not given x, but we know from the value box x=.8y (y equals number that did not pass writing)
PDriving No PDriving Total
Pass Writing .7x (this is also .8y) .3x x
No Pass Writing .2y 0 .2y
Total (.8y+.2y) = y .3x
INSUFFICIENT because we don't know Y or X
A+B = we know there are 188 students
so, y+.3x = 188
And we know from the box that .7x = .8y
solve for x and you can get .7x
y+.3x = 188
.7x=.8y
This one is tricky because you have to pay attention to the values and what it references.
Stacey I'm not really a loser, you've just been very helpful so shoutouts to you, but I'll stop.
For whoever wrote this post - I say practice your overlapping problems and practice the box and circle tips that MGMAT wrote in the word translation book.
I will do the problem and get back to you tomorrow if you do not understand it after doing the chart.
Actually...for Stacey...I will do it now.
PDriving No PDriving Total
Pass Writing .7x .3x x
No Pass Writing 0
Total .3x
You want to know what .7x is - so what is x could be a rephrasing
1) You know there are 188 sixteen year olds. That does not give us x, that gives us the total students so INSUFFICIENT (Hi stacey)
PDriving No PDriving Total
Pass Writing .7x .3x x
No Pass Writing 0
Total .3x 188
2) You now 20% of the people that passed the practical driving, failed the written. We are not given x, but we know from the value box x=.8y (y equals number that did not pass writing)
PDriving No PDriving Total
Pass Writing .7x (this is also .8y) .3x x
No Pass Writing .2y 0 .2y
Total (.8y+.2y) = y .3x
INSUFFICIENT because we don't know Y or X
A+B = we know there are 188 students
so, y+.3x = 188
And we know from the box that .7x = .8y
solve for x and you can get .7x
y+.3x = 188
.7x=.8y
This one is tricky because you have to pay attention to the values and what it references.
Stacey I'm not really a loser, you've just been very helpful so shoutouts to you, but I'll stop.
For whoever wrote this post - I say practice your overlapping problems and practice the box and circle tips that MGMAT wrote in the word translation book.
3 posts Page 1 of 1