SOLUTION: In a class of 16 students, 13 students took a Math test, 10 students took Science test, and 9 students took both tests. How many students did not take any of the tests?

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Question 1002622: In a class of 16 students, 13 students took a Math test, 10 students took Science test, and 9 students took both tests.
How many students did not take any of the tests?
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20850) (Show Source):
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In a class of students,
if students took a Math test, so far students did not take a Math test
if students took Science test, and students took both tests, then there was student who took Science test only
so, if students took a Math test and student who took Science test only, means students took either a Math test or Science test or both
so students did not take any of the tests

Answer by ikleyn(52855) (Show Source):
You can put this solution on YOUR website!
.
In a class of 16 students, 13 students took a Math test, 10 students took Science test, and 9 students took both tests.
How many students did not take any of the tests?
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How many students took the Math test only and didn't took the Science test?
Their number is 13 - 9 = 4.

How many students took the Science test only and didn't took the Math test?
Their number is 10 - 9 = 1.

How many students took at least one, the Math or the Science test?
Their number is 9 + 4 + 1 = 14.

Hence, 16-14 = 2 students didn't take any of the tests.

Answer. 2.