Gmatprep998
In a certain group of women, 70 percent of the women were employed and 25 percent did not have a graduate degree. Which of the following statements cannot be true?
I. No woman in the group who had a graduate degree was unemployed
II. Less than half of the women in the group were employed and had a graduate degree
III. The number of unemployed women with a graduate degree was 50 percent greater than the number of employed women without a graduate degree
A. I only
B. II only
C. III only
D. I and III only
E. II and III only
Source: e-GMAT Scholaranium
We can make a 2 by 2 ..
...........E.............UE..Total
G........a............... b.....75
NG.....c............... d......25
Total..70...........30.......100
We are looking for CANNOT be true..
I. No woman in the group who had a graduate degree was unemployed
This means b=0,but a can be max 70, and this makes the least value if b as 5.
Cannot be true.
II. Less than half of the women in the group were employed and had a graduate degree
This means a<50. Possible, as max value of a will be when c is 0, so 70, and min value will be when c is max that is 25, so a = 70-25=45<50.
Can be true.
III. The number of unemployed women with a graduate degree was 50 percent greater than the number of employed women without a graduate degree.
This means b=1.5c. Possible ..
a+b=75...a+c=70, so b-c=75-70=5 or 1.5c-c=5...c=10 and b =15.
Can be true.
Only I cannot be true
A
1. How did you know when to use?
2. Could you share few more sums like this?
Thank you.