Tough DS from Kaplan 800.

I am getting 'B"
whats OA ?
this is how I solved
pick a number for # of students = 36 LCM of 3,4,9
Thus number of faculty = 4 since ratio is 1:9
# of female student = 2/3 of 36 = 24
# of female faculty = 1/4 of 4 = 1
ratio = (24+1)/(36+4)

Or pick smart numbers and solve for the ratio


ratio 1:9

12 faculty

108 students

2/3*108 = 72

1/4*12 = 3

72+3/120 = 5/8

B)

Fac/St =1/9

2/3*S=F
1/4 faculty is female

9,3,4 so the ideal number to plug in 36

so there are 4 faculty, and 36 students

2/3 of students is female thats is 24 female stduents

1/4 female fucaulty is 1

combined is 40 and female bothe faculty and students is 25

25/40 -- > 5/8 it is OA B

vishu

Hi guys I found this Q very tough.Jus curious to know if such tough questions are expected in the real test???

I wont be surprised if u get one !!!

vishu

Faculty = F
Student = S

S/F = 9

For Students;
Female = 2/3 S

For faculty:
Facultuy = 1/4 F

Now total females/ total people: ( 2/3S + 1/4(S/9) )/ S + S/9 ( using previous equation to convert F into S)
= 5/8

IMO B

Questions like these can be difficult if you try to do normal math. It becomes a much easier problem when you pick numbers to attack this problem as the previous posters have demonstrated.

Here is another way.
f:s = 1: 9. So totally 1+9= 10. (here the entire problem deals with ratios; fraction is a synonym for ratio. So we can drop the x ie. we dont need to say f:s = 1x: 9x, so totally 10x)

From the q we have females are
2/3 of 9 and 1/4 of 1 ie. 18/3 + 1/4.

The q asks for ratio (or fraction) of females to combined total.

ie (18/4 + 1/4) / 10.

=> 5/8


HT Helps.

One can be almost sure to expect q of this this type on GMAT. This is a moderately tough question, probably a 600 -650 level.

Thanks for all the response guys.

Answer is (B)