# SAT Practice Test 4, Section 8: Questions 6 - 10

Given:
The figure

r = 50

To find:
s + t + u

Solution:
Topic(s): Pairs of angles

Given r = 50
u = r = 50 (corresponding angles)
s = u = 50 (vertical angles)
t = 180 – u = 180 – 50 = 120 (complementary angles)

s + t + u = 50 + 50 + 120 = 220

Given:
Line l is perpendicular to the y-axis and passes through the point (5, -3)

To find:
The equation of line l

Solution:
Topic(s): Coordinate geometry

Line l is perpendicular to the y-axis.

This means it is a horizontal line (slope m = 0) that passes through the point (5, – 3).
The y-intercept will be at –3.
So, the equation of the line is y = – 3

Answer: (C) y = – 3

Given:
The profit obtained by selling x units is given by the function
p(x) = 17x – (10x + b), where b is a constant
300 units were sold for a profit of \$1,900

To find:
The value of b

Solution:
300 units sold means x = 300
\$1,900 profit means p(x) = 1900

Substitute into the function:

p(300) = 17 × 300 – (10 × 300 + b) = 1900
⇒ 5100 – 3000 – b = 1900
b = 2100 – 1900 = 200

To find:
The number that results when an integer is multiplied by itself CANNOT end in which of the following digits

Solution:
We need to eliminate the answers that are ending digits when an integer is multiplied by itself.

Given:
A bag with only red, blue and yellow marbles

The probability of selecting a red marble is

The probability of selecting a red marble is

To find:
The total number of marbles in the bag

Solution:
Topic(s): Probability

This means that the total number of marbles must be a multiple of 4 and a multiple of 6.

Check the answers to find the one that is a multiple of 4 and a multiple of 6.