12.Practice.Tests.for.the.SAT_2015-2016_1128p

12 Practice Tests for the SAT
Practice Test Three Answers and Explanations I
31 l
10. A
Difficulty: Medium
Strategic Advice: In complex geometry problems, look for
parts in common between the various shapes.
Getting to the Answer:
Since angles of a triangle add up to 180 degrees, then
50 + h + g = 180 and 70 + z + g = 180.
So,
g= 130-h
g= l lO-z
130-h= 110-z
11. c
h = 20 +z
Difficulty: Medium
Strategic Advice: Use any diagram given to your full
advantage. They're usually the key to a great score.
Getting to the Answer:
There are five tick marks between 0 and l. Therefore,
l 3 . 3 l 2
p = - and q = - so p - q 1s - - - = -.
s s ' s s s
12. c
Difficulty: Medium
Strategic Advice: Round up when the succeeding digit is 5
or above. Round down if the succeeding digit is less than 5.
Getting to the Answer:
Therefore, 16.763 rounds to 16.8 because 6 is greater
than 5.
13. D
Difficulty: Medium
Strategic Advice: The square root of a negative number
is undefined. Backsolving might let you solve this problem
more quickly.
Getting to the Answer:
0 ::;x2 - 4
4 ::;x2
2 ::;xor -2 x
f (x) is undefined for any values of x that are not within
the above range. Since 0 is not within the range, (D) is
correct.
14. B
Difficulty: High
Strategic Advice: You are asked to Pick Numbers to plug
into the function. Use the resulting information to confirm or
eliminate each of the choices.
Getting to the Answer: Pick Numbers to try to eliminate
choices. Choice I says t > 0. If you select l for x, then y =
4, z = 0, and t = 0. Therefore, I is wrong. Eliminate (A), (C),
and (E). The only difference between the remaining choices
is whether or not Ill is correct, so test it first. Try using 4 for x.
This means that y = 13, z = 14, and
t = 7, which is odd. So Ill is not correct and (B) is the correct
answer.
Although you don't need to check II, it is correct because no
matter what you get for y, z will always be even. If y is odd,
then l is added to it to get z, which would always make z
even. If y is even, then 4 is subtracted, and z is still even.
Therefore, no matter what, z will always be even.
15. D
Difficulty: High
Strategic Advice: When you have multiple variables and
multiple equations, use substitution or elimination to
determine the answer. Often, one method is much easier
than the other.
Getting to the Answer:
It is also important to note you are not being asked for a or
b, but rather a - b. Very often in problems like this you do
not need to solve for the individual variables; rather, you can
manipulate the equations to find the desired expression.
The easiest way to find a - b is through elimination. Multiply
the second equation by -2, then add the equations
together:
3a + Sb - 4c = 12
-2a - 6b + 4c = 8
a -b =20
By eliminating the variable c, the value of a - b was
determined. (D) is the correct answer.