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

l 2 Practice Tests for the SAT
Practice Test Seven Answers and Explanations 653
I
Getting to the Answer:
8. A
f(2) = 2 + 4 = =3
2 2
g(2) = 22 - 6=4-6 =-2
3-(-2) =3+2=5
Difficulty: High
Strategic Advice: This question involves the range-that is,
all possible values-of d(w). Think about the limits of the
function. Is there a number it must be smaller than? Is there
a number it must be larger than?
Getting to the Answer:
w2 0, since any real number squared must be positive.
w2 + 11
VW2+11
The only answer choice that is not greater than or equal
to 1 is (A).
9. 5.50
Difficulty: Low
Strategic Advice: Be careful not to lose points on simple
arithmetic questions.
Getting to the Answer:
Buying 12 tickets separately costs 12 times $1.50, or
$1 8. Buying a dozen tickets at once costs $ 1 2.50, so the
difference in cost is $ 1 8 - $12.50, which equals $5.50.
10. 49
Difficulty: Low
Strategic Advice: Notice that a side of square C is made up
of a side of square A and a side of square B. The area of a
square is the square of the length of a side.
Getting to the Answer:
Since the area of square A is 9, its side is 3; since the area
of square B is 16, its side is 4. This makes a side of square C
equal to 3 + 4 = 7, so its area is 49.
11. 3 5 6
Difficulty: Medium
Strategic Advice: In this problem, you need to work with a
system of equations.
Getting to the Answer:
You're asked for the value of rs, so solve for t in terms of s in
the first equation and plug that into the second equation.
-4=5
t
s=9t
2- =t
9
Plug% for t in the second equation:
5rt + 2 = 6
5r(%) + 2 = 6
12. 6 or 8
2 rs =4
9
rs = 4 x .2.
5
rs = 36
5
Difficulty: Medium
Strategic Advice: This can be solved by trial and error. Try
different values of n until you find one that fits the given
conditions.
Getting to the Answer:
You want 3n + 5 to be between 20 and 40. If n = 6, then
3n + 5 = 3(6) + 5 = 23, which is a prime number between
20 and 40. So 6 is a correct answer. Another correct answer
is 8, since 3(8) + 5 = 29, which is also a prime number
between 20 and 40.
13. 21 or 28
Difficulty: Medium
Strategic Advice: This problem requires an understanding
of how ratios work.
Getting to the Answer:
Since the ratio of boys to girls in the class is 3 to 4, the total
number of students in the class must be a multiple of 3 +
4, or 7. The multiples of 7 between 20 and 30 are 21 and
28. Either answer is correct.
14. 80
Difficulty: Medium
Strategic Advice: Find how many CDs she can fit in length,
then in width, then in height.