Venn Diagram Problem for OG 11

**rachmak** · 10-21-2006, 05:25 PM

#239 from Official Guide 11

Of the 200 students at College T majoring in one or more of the sciences, 130 are majoring in chemistry and 150 are majoring in biology. If at least 30 of the students are not majoring in either chemistry or biology, then the number of sutdents majoring in both chemistry and biology could be any number from:

A) 20 to 50
B) 40 to 70
C) 50 to 130
D) 110 to 130
E) 110 to 150

I simply don't understand the given solution from the answer key. Can someone provide a simpler explanation? Is it necessary to use Venn Diagram?

Thanks!

**GREMAT** · 10-21-2006, 05:51 PM

200=c+b-cb+30
200=130+150-cb+30
cb=110
this is min. number of c&b, the max number is 130 (when all chemistry majors both in c and b)
Ans D

**G.Unit** · 10-22-2006, 05:53 AM

Some Official Guide answers explaination tends to be lengthy and unefficient.

**G.Unit** · 10-22-2006, 05:55 AM

That's a good explaination !!!

**ashraf Ali** · 10-22-2006, 08:08 AM

i have some undrstanding problem in this question
"If at least 30 of the students are not majoring in either chemistry or biology"
does this mean neither chemistry nor biology? (neither according to the formula total=groupA+groupB-both+neither)
if it says either chemistry and biology then it means both
but it used either ...or format
if i am wrong por favor, el señor correct me.
por favor, el señor clarify it.

**ashraf Ali** · 10-22-2006, 08:10 AM

thanks bye

**rachmak** · 10-22-2006, 05:16 PM

fantastic explanation! thanks

**_GMAT_** · 10-24-2006, 03:22 AM

Is it D...

**ashraf Ali** · 10-24-2006, 04:50 AM

Originally Posted by ashraf Ali

i have some undrstanding problem in this question
"If at least 30 of the students are not majoring in either chemistry or biology"
does this mean neither chemistry nor biology? (neither according to the formula total=groupA+groupB-both+neither)
if it says either chemistry and biology then it means both
but it used either ...or format
if i am wrong por favor, el señor correct me.
por favor, el señor clarify it.

GREMAT por favor, el señor clarify the dilema of mine.
am i making blunder mistake?