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

12 Practice Tests for t h e SAT
646 Practice Test Seven Answers and Explanations
13. A
Difficulty: Medium
Strategic Advice: For t h is coordinate geometry probl em, t h e
perimeter is t h e sum of t h e l engt h s of a ll t h e sides.
Getting to the Answer:
First sketc h t h e triang l e. We h ave l abe l ed t h e points A, B,
and C.
y
c (2, 5)
T e l engt h of AB is simp l y t h e difference in t h e x-coordinates,
t h at is, 5 - (- 1) = 6. Finding t h e l engt h s of BC and AC is
trickier. Divide triang l e BC into two rig h t triang l es by drawing a
perpendicu l ar l ine from C to side AB, as s h own.
y
0 x
Now AC and BC are t h e h ypotenuses of rig h t triang l es-you
can find t h eir l engt h s using t h e Pyt h agorean t h eorem.
(AC) 2 = 4 2 + 3 2 = 16 + 9 = 25
So AC= \/25 = 5.
Simi l ar l y, (BC) 2 = 4 2 + 3 2 , so BC = 5.
So t h e perimeter is 6 + 5 + 5 = l 6.
14. D
Difficulty: Medium
Strategic Advice: Simp l y count a ll t h e possibi l ities.
Getting to the Answer:
If t h e numbers must h ave a tens digit greater t h an 5, t h ey
must 60 or greater. Since t h ey are two-digit numbers, t h ey
must be l ess t h an 1 00. Since t h e units digit is odd, t h ey must
be odd. So you need to count a ll t e odd numbers between
60 and 1 00. We ll , t h ere are 5 suc h numbers wit h a tens digit
of 6: 61, 63, 65, 67, and 69. Simi l ar l y, t h ere wi ll b e 5 more
numbers wit h a tens digit of 7, 5 more wit h a tens digit of 8,
and anot h er 5 wit h a tens digit of 9. T h at's 5 + 5 + 5 + 5, or
20 suc h numbers.
15. B
Difficulty: Medium
Strategic Advice: In t h is percent word probl em, since percent
means h undredt h s, a percent= 1 g 0
and b percent= 1 0 .
Getting to the Answer:
So a percent of b percent of 200 =
x J!.__ x 200 = 200ab
=
ab
100 100 10, 000 50
16. c
Difficulty: Medium
Strategic Advice: Read carefu ll y.
Getting to the Answer:
If t h e tricate of z is 3, at means t at one-t h ird of t h e sma ll est
mu l tip l e of 3 greater t h an z is 3. at is, t h e sma ll est mu l tip l e
of 3 greater t h an z is 3 x 3 = 9. T h e sma ll est mu l tip l e of 3
greater t h an z wi ll b e 9 on l y if 6 z < 9. C h oice (C) is t h e on l y
number in t h is range, so it must be correct.