vladmire wrote:Practice Test 1 question states
How many of the students in a certain class are taking both a history and a science course?
(1) Of all the students in the class, 50 are taking a history course.
(2) Of all the students in the class, 70 are taking a science course.
a. 1
b 2
c both
d either alone
e or neither suff.
Is there enough information to create a venn diagram or a formula. OA - e.
you can do a venn diagram here.
i can't create one within the bounds of a forum post, but imagine that the following post has the form of a venn diagram, with one circle at left and one circle at right.
imagine that the left-hand number is in the left circle but
not in the right circle; vice versa for the right-hand number; and that the center number is in the overlapping region of both circles.
let the left-hand circle represent the history class, and the right-hand circle the science class.
in this case, the 2 numbers at left (excluding only the right-hand number) must sum to 50, and the 2 numbers at right (excluding only the left-hand number) must sum to 70.
try different numbers in the middle. it turns out that you can put any number from 0 to 50 (inclusive) in the middle; here are two examples:
30
20 50 (where the '20' is placed first)
40
10 60 (where the '10' is placed first)
since the middle number is queried, this proves that the two statements together are insufficient.
Ron has been teaching various standardized tests for 20 years.
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