Night reader wrote:In 1997, N people graduated from college. If 1/3 of them received a degree in the applied sciences, and, of those, 1/4 graduated from a school in one of six northeastern states, which of the following expressions represents the number of people who graduated from college in 1997 who did not both receive a degree in the applied sciences and graduate from a school in one of six northeastern states?
(A) 11N/12
(B) 7N/12
(C) 5N/12
(D) 6N/7
(E) N/7
I was unable to solve this
We can plug in our own value for N. We should choose a number that is divisible by the denominators of the two fractions in the problem (1/3 and 1/4).
Let N = 3*4 = 12.
Received a degree = 1/3 * 12 = 4.
Received a degree and graduated from one of the six schools = 1/4 * 4 = 1.
Since only 1 person both received a degree and graduated from one of the six schools, the number who didn't do both = 12-1 = 11. This is our target.
Now we plug N=12 into all the answers to see which yields our target of 11.
Only answer choice A works:
11/12*N = 11/12 * 12 = 11.
The correct answer is
A.
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