All PSAT Math Resources
Example Questions
Example Question #15 : Evaluating Expressions
x * y = –a, a – x = 2a. What is y?
1
-2
a
-a
Insufficient Information.
1
Use the second equation to find x in terms of a. Plug it back in the second equation, that will give you 1 = y.
Example Question #21 : Evaluating Expressions
The projected sales of a movie are given by the function s(p) = 3000/(2p + a) where s is the number of movies sold, in thousands; p is the price per movie, in dollars; and a is a constant. If according to projections, 75,000 cartidges will be sold at $15 each, how many movies are sold at $20 each?
200,000
50,000
60,000
20,000
150,000
60,000
You set up the equation to solve for a.
75 = 3000/(2(15) + a)
a = 10
You then set up the formula again for each movie costing $20, s(20) = 3000/(2(20) + 10), and solve for x, the number sold, giving you 60.
Example Question #22 : Evaluating Expressions
Half of one hundred divided by five and multiplied by one-tenth is __________.
10
1
1/2
5
2
1
Let's take this step by step. "Half of one hundred" is 100/2 = 50. Then "half of one hundred divided by five" is 50/5 = 10. "Multiplied by one-tenth" really is the same as dividing by ten, so the last step gives us 10/10 = 1.
Example Question #23 : Evaluating Expressions
Let x&y be defined as (x – y)xy . What is the value of –1&2?
3
–1/3
1/9
–3
–1/9
1/9
We are told that x&y = (x – y)xy .
–1&2 = (–1 – 2)(–1)(2) = (–3)–2
To simplify this, we can make use of the property of exponents which states that a–b = 1/(ab ).
(–3)–2 = 1/(–3)2 = 1/9
The answer is 1/9.
Example Question #21 : Expressions
If 18 – w is 8 less than 32, what is the value of ?
–3
2
–2
3
–6
2
We need to rewrite this problem in mathematic terms.
8 less than 32 can be written as 32 – 8
so we will get the equation
18 – w = 32 – 8.
Now, we need to solve for w.
–w = 32 – 8 – 18
–w = 6
w = –6
Find the value of the given expression, , by plugging in –6 for w.
Example Question #23 : Evaluating Expressions
If x and y are integers such that x > y > 0 and x2 + y2 = 100
Which of the following can be the value of x + y?
I. 10
II. 12
III. 14
IV. 16
V. 18
12
16
18
14
10
14
Note that x must be greater than y and that y must be greater than 0. This means that x and y are different, positive integers. In addition, the sum, x2 + y2 must equal to 100. If we list squares beginning from the square of the first integer greater than 0 (12) up to the square of the greatest integer less than 100 (92) we will get:
1, 4, 9, 16, 25, 36, 49, 64, 81
We must observe that the only two numbers that will add up to 100 are 36 and 64.
Remember that x > y > 0 and that x2 + y2 =100.
This means that x must be and y must be
When we solve for x and y we get:
x = 8
and y = 6.
Therefore, x + y can only be 14.
Example Question #24 : Evaluating Expressions
If , which of the following has to be true?
Plug in numbers for each alternative. If both sides of the inequality are multiplied by 2, the result is the original inequality, . The other options fail (if confused, try plugging in as a positive, as a negative).
Example Question #22 : Evaluating Expressions
Billy began lifting weights in February. After 6 months, he can lift 312 lbs, a 20% increase in the amount he could lift in February. How much weight could Billy lift in February?
Example Question #733 : Algebra
A metal rod is 36 inches long and divided into 3 sections. The middle section is twice as long as the first section. The third section is 4 inches shorter than the first section. How long are the sections?
None of the above answers
The first piece is 6 inches, the second piece is 10 inches and the third piece is 20 inches
First piece is 20 inches, the second piece is 10 inches and the third piece is 6 inches
The first piece is 15 inches, the second piece is 15 inches and the third piece is 6 inches
First piece is 10 inches, the middle piece is 20 inches, and third piece is 6 inches long.
First piece is 10 inches, the middle piece is 20 inches, and third piece is 6 inches long.
Assume the first section equals inches, then the second(or the middle section) must be equal to and the third piece must be equal to .
and now you solve for which equals 10. Hence the middle piece must be equal to 20 inches and the third piece is only 6 inches long.
Example Question #734 : Algebra
A B
1 2
2 4
3 10
5 34
Using the table above, please select the answer below that expresses the relationship between A and B.
By testing the answers, it can be seen that the only equation to satisfy all cases in the table above is
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