SOLUTION: in a class of 30 students, 18 students study history, 16 study geography and 3 study neither subject. how many students undertake geography but not history

Algebra.Com
Question 1007091: in a class of 30 students, 18 students study history, 16 study geography and 3 study neither subject. how many students undertake geography but not history
Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.
In a class of 30 students, 18 students study history, 16 study geography and 3 study neither subject. How many students undertake geography but not history?
------------------------------------------------------------------------ 
How many students of the class study at least one of the two subjects, history or geography? 30 - 3 = 27 students.

Now add 18 who study history and 16 who study geography. You will get 18 + 16 = 34.

Why it is more than 27? - It is because some of 18 + 16 study both history and geography.

How many students study both subjects?  The answer is: (18 + 16) - 27 = 34 - 27 = 7. 

Now we know that 16 students study geography; of them 7 study history.

Thus, it is easy to determine the number of those who study geography only.
It is 16 - 7 = 9.

Answer. The number of students who study only geography is 9.


RELATED QUESTIONS

All 30 students in a class study at least one of the two subjects History and Geography. (answered by ikleyn)
In a class of 80 students, every student studies Economics or Geography or both. If 65... (answered by Jc0110)
In a class of 31 students , 22 study physics , 20 study chemistry & 5 study neither, how (answered by stanbon)
In a class of 100 students, it is known that 45 study mathematics, 26 study chemistry and (answered by richwmiller)
In a class of 100 students, it is known that 45 study mathematics, 26 study chemistry and (answered by Theo)
1) A survey in a college indicates that 32 students study mathematics 30 students study (answered by richwmiller)
A survey in a college indicates that 32 students study mathematics 30 students study... (answered by richwmiller)
In a group of 80 high school student, 30 study Spanish, 40 study French, and 25 study... (answered by richwmiller)
In a group of 80 high school student, 30 study Spanish, 40 study French, and 25 study... (answered by stanbon)