Problem Solving

30% of the students of a university are studying Engineering.60 percent of students are male and the number of female students studying medicine is 15% of all of the students.what percentage of the students studying Engineering is male?

1)12%
2)16.7%
3)9%
4)5%
5)8%

the number of female students studying medicine is 15% of all of the students -> .15S=x*0.4S and x=150/4=37.5 % of female students are studying medicine, the rest are assumed a) either to study engineering or b) to study Engineering and not to study anything
case a) 37.5% of females study engineering, which is 37.5 * 40% of total students, leaves 15% of all students who study Engineering
case b) less than 37.5% of females study engineering, which is less than 15% of all students who study Engineering.

Considering 60% of all students are male, only male >15% can study Engineering.

ans b, 16.7%

I think the answer is D) 5%

I assumed students studying Engineering and Math are mutually exclusive. So,

Assume total students = 100
Male - 60 (given)
So Female - 40
Female Math students - 15 (given)
Female Engg students - 25 (40-15)
Total Engg - 30 (given)
So Male Engg - 5 (30-25)

lets assume,that we have 100 students in total.

then 15% of all of the students = .15*100=15 female students studying medicine

since in total we have 40 females (0.4*100), then 40-15=25 females study engineering

since we have 30 (0.3*100) students studying engineering 30-25=5 males studying engineering

5/100=5%

the ratio 1/6 returns 16.7%
accordingly 1/6=10/60 would return 9, 18 and 24 students for 15%,30% and 40% of 60 students. Or take # students as 120, 180 etc.

we don't know how many female students study engineering; we only know that 15 female students study medicine and can effectively infer:
- 15 female students studying medicine may study engineering too (no room for assuming mutual exclusiveness here, as no restriction is put in q.)
- 15 female students studying medicine may not study engineering

IMO B, use 2X2 matrix method: easy: reliable: faster

nice, worth to stress

oldheaven wrote:30% of the students of a university are studying Engineering.60 percent of students are male and the number of female students studying medicine is 15% of all of the students.what percentage of the students studying Engineering is male?

obviously not 5/100 but 5/30 with the same proportion set as 1/6

Nice question. I agree with pemdas. It should be 5/30. as we need to find it as a percentage of total engineering canditates.

user123321

Question is "what percentage of the students studying Engineering is male?"

We have found out the the number of male engineering students is 5 out of a pool of 100 students.

The answer should be B) 16.7% - which is x percent of 30 engineering students equals 5 male engineering students [(x/100)*30=5 or (5/30)*100=x]

The answer choice D) 5% is incorrect because it is the percentage of male students from a pool of 100 students (includes Engineering and Medicine) while the question asks from a pool of 30 engineering questions.

Note: I have considered the total pool of students to be 100 since we are dealing with percentages.

Thanks,
Bharath-[/b]

yep, I got where I was wrong. thnx a lot, guys!

pemdas wrote:the number of female students studying medicine is 15% of all of the students -> .15S=x*0.4S and x=150/4=37.5 % of female students are studying medicine, the rest are assumed a) either to study engineering or b) to study Engineering and not to study anything
case a) 37.5% of females study engineering, which is 37.5 * 40% of total students, leaves 15% of all students who study Engineering
case b) less than 37.5% of females study engineering, which is less than 15% of all students who study Engineering.

Considering 60% of all students are male, only male >15% can study Engineering.

ans b, 16.7%

I really enjoy your approach and style, thank you pemdas.