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

1 2 Practice Tests for t h e SAT I
Practice Test One Answers and Explanations
131
2. D
Difficulty: Low
Strategic Advice:
l Simp l ify t h e equation b y getting rid of t h e
i ke terms. Sometimes pro b l ems t h at seem comp l icate d
h ave a very straig h tforwar d so l ution, particu l ar l y if t h ey
appear ear l y in t h e section.
Getting to the Answer:
- a 3 + = a 3 + 9
b 2 =9
b=3 or-3
3. c
Difficulty: Low
Strategic Advice: You may t h ink t h is pro b l em is
comp l icated b ecause it is l engt h y. T h e tric k, as wit h a ll word
pro b l ems, is to rea d carefu ll y and get to t h e h eart of t h e
question.
Getting to the Answer:
Add t h e l owest origina l mi l e time to t h e l owest additiona
time: 5 l
+ 1=6
Add t h e h ig h est origina l mi l e time to t h e h ig h est additiona
time: l
7 +2=9
Minimum and maximum mi l e times: 6 minutes and
9 minutes
4. E
Difficulty: Medium
Strategic Advice: We know t h at one revo l ution is 360°.
Since t h is h appens every 1.5 seconds, (A) and (B) are
definite l y too l ow.
Getting to the Answer:
T h e b a ll goes around
1 1 _ = \ 0 5
° = 2 3
° times, for a tota l of
2 3
° (360°) = 2,400°.
5. E
Difficulty: Medium
Strategic Advice: You can eit h er Backso l ve or set up an
equation and so l ve a l ge b raica ll y.
Getting to the Answer:
Backso l ving works we ll h ere since t h ere are num b ers in t h e
answer c h oices.
(A) Origina l fraction = t• new fraction t:.
1 t:.
5 t· so (A)
1s wrong.
(B) Origina l fraction = ill 4 , new fraction = ill I + t:. . so
(B) is wrong.
(C) Origina l fraction = i· new fraction = t ,;:. t· so (C) is
wrong.
(D) Origina l fraction = i· new fraction= 4 ,;:.
5 t· so (D)
1s wrong.
(E) Origina l fraction = 1 i, new fraction = i = t· so (E)
1s correct.
To so l ve t h e pro b l em a l ge b raica ll y, first trans l ate eac h sentence
into an equation:
!5._ = J_
y 3 and 1'.. = J_
2 2
So l ve t h e first equation for x in terms of y, t en p l ug t h is
into t h e second equation and so l ve for y (t h e denominator
of t h e origina l fraction).
3x=y
x=
1'..
l'.'.. 3
3 -1
_ l
1'.. 2
3 -1 = 1'.. 4
4y- 12 =3y
y= 12
---y- - 2
6. c
Difficulty: Medium
Strategic Advice: W h en t h e SAT presents measurements
in different units, convert everyt h ing to t h e same unit of
measure and pay attention to t h e question t h at is asked.
Getting to the Answer:
First, convert mi l es per h our to mi l es per minute; to do t h is,
divide b y 60.
Because 4·o = 78, t h e p l ane can trave l 78 mi l es per minute.
Ten seconds is one-sixt h of a minute, so divide b 78 y
6 to find t h e num b er of mi l es t h e p l ane can trave l in l 0
seconds· . _Z§_ 6 = 13 .