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12 Practice <strong>Tests</strong> <strong>for</strong> <strong>the</strong> <strong>SAT</strong><br />

Practice Test Three Answers and Explanations I<br />

291<br />

12. E<br />

Difficulty: High<br />

Strategic Advice: Use points C and D to determine <strong>the</strong><br />

slope of <strong>the</strong> line and <strong>the</strong> y-intercept, which will give you <strong>the</strong><br />

equation <strong>for</strong> <strong>the</strong> line. Then go through <strong>the</strong> answer choices<br />

to see which o<strong>the</strong>r point fits into that equation.<br />

Getting to <strong>the</strong> Answer:<br />

Y 2<br />

-y 1<br />

Slope =- X2 - Xl<br />

5-2 =<br />

i =l<br />

2-(-1) 3<br />

Find <strong>the</strong> y-intercept (when x = 0):<br />

Slope = 1 = -1...=L = 1-=-t = -2 + y<br />

-1 -0 -1<br />

1 =-2 + y<br />

3=y<br />

Line equation:<br />

y= 1 (x) + 3<br />

y=x+3<br />

Eyeball <strong>the</strong> answer choices to see which one might fit.<br />

(E) (1, 4)<br />

4=1+3<br />

4=4<br />

Choice (E) is correct.<br />

13. E<br />

Difficulty: Medium<br />

Strategic Advice: First, determine <strong>the</strong> pattern in <strong>the</strong><br />

repeating decimal. Then determine which of <strong>the</strong> numbers<br />

from 0 to 9 <strong>the</strong> 5 1st digit will equal.<br />

Getting to <strong>the</strong> Answer:<br />

0.04761 90476 1904761 90 ...<br />

The pattern repeats after every 6 digits.<br />

So, 0 begins with <strong>the</strong> 1st, 7th, 13th, 19th, 25th, 31st, 37th,<br />

43rd, 49th.<br />

The question is <strong>for</strong> <strong>the</strong> 5 1st digit. So if <strong>the</strong> 49th digit is 0,<br />

<strong>the</strong>n <strong>the</strong> 51 st digit is 7.<br />

14. B<br />

Difficulty: Medium<br />

Strategic Advice: Probability is <strong>the</strong> ratio of <strong>the</strong> number<br />

of desired outcomes to <strong>the</strong> total number of possible<br />

outcomes. Determine each of <strong>the</strong> two numbers after<br />

Sharon takes out a coin that is not a quarter.<br />

Getting to <strong>the</strong> Answer:<br />

# of desired outcomes = # of quarters = 6<br />

# of possible outcomes = # of coins<br />

=original # - 1 = (6 + 5 + 10) - 1 = 20<br />

6<br />

Probability 2 0 = 3<br />

1 0<br />

Choice (B) is correct.<br />

15. c<br />

Difficulty: Medium<br />

Strategic Advice: Go through each answer choice to see if<br />

it is possible given <strong>the</strong> rules in <strong>the</strong> question stem.<br />

Getting to <strong>the</strong> Answer:<br />

(A) a + b This could never be an integer. Only an integer<br />

plus an integer will result in an integer. An integer plus a<br />

fraction will be a fraction.<br />

(B) a - b This could never be an integer. Only an integer<br />

minus an integer will result in an integer. An integer minus a<br />

fraction will be a fraction.<br />

(C) ab This could be an integer. For example,<br />

1<br />

a=2 b=-<br />

' 2<br />

ab =2(t) = 1<br />

(D) 2a - b This could not be an integer <strong>for</strong> <strong>the</strong> same<br />

reason as (B). 2a is an integer because a is an integer,<br />

but b is still a noninteger.<br />

(E) E_ Again, take a = 2 and b = _!_.<br />

a 2<br />

1<br />

b - 1 1<br />

- = = -- = -. Th' 1s . 1s not an . integer.<br />

a 2 2x2 4<br />

Choice (C) is correct.

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