PSAT Math : PSAT Mathematics

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #791 : Psat Mathematics

\dpi{100} \small -2y+7>-7+y

Given the inequality above, which of the following MUST be true?

Possible Answers:

\dpi{100} \small y>\frac{-14}{3}

\dpi{100} \small y<5

\dpi{100} \small y<\frac{-14}{3}

\dpi{100} \small y>\frac{14}{3}

\dpi{100} \small y>-5

Correct answer:

\dpi{100} \small y>-5

Explanation:

\dpi{100} \small -2y+7>-7+ySubtract  from both sides:

Subtract 7 from both sides:

Divide both sides by \dpi{100} \small -3:

Remember to switch the inequality when dividing by a negative number:

Since \dpi{100} \small y<\frac{14}{3} is not an answer, we must find an answer that, at the very least, does not contradict the fact that  is less than (approximately) 4.67.  Since any number that is less than 4.67 is also less than any number that is bigger than 4.67, we can be sure that  is less than 5.

Example Question #792 : Psat Mathematics

A factory packs cereal boxes. Before sealing each box, a machine weighs it to ensure that it is no lighter than 356 grams and no heavier than 364 grams. If the box holds  grams of cereal, which inequality represents all allowable values of ?

Possible Answers:

Correct answer:

Explanation:

The median weight of a box of cereal is 360 grams. This should be an allowable value of w. Substituting 360 for w into each answer choice, the only true results are:

and:

Notice that any positive value for w satisfies the second inequality above. Since w must be between 356 and 364, the first inequality above is the only reasonable choice.

Example Question #793 : Psat Mathematics

What values of x make the following statement true?

|x – 3| < 9

Possible Answers:

–12 < x < 6

–3 < x < 9

x < 12

6 < x < 12

–6 < x < 12

Correct answer:

–6 < x < 12

Explanation:

Solve the inequality by adding 3 to both sides to get x < 12.  Since it is absolute value, x – 3 > –9 must also be solved by adding 3 to both sides so: x > –6 so combined.

Example Question #794 : Psat Mathematics

If –1 < w < 1, all of the following must also be greater than –1 and less than 1 EXCEPT for which choice?

Possible Answers:

3w/2

w/2

|w|

|w|0.5

w2

Correct answer:

3w/2

Explanation:

3w/2 will become greater than 1 as soon as w is greater than two thirds. It will likewise become less than –1 as soon as w is less than negative two thirds. All the other options always return values between –1 and 1.

Example Question #795 : Psat Mathematics

Solve for .

Possible Answers:

Correct answer:

Explanation:

Absolute value problems always have two sides: one positive and one negative.

First, take the problem as is and drop the absolute value signs for the positive side: z – 3 ≥ 5. When the original inequality is multiplied by –1 we get z – 3 ≤ –5.

Solve each inequality separately to get z ≤ –2 or z ≥ 8 (the inequality sign flips when multiplying or dividing by a negative number).

We can verify the solution by substituting in 0 for z to see if we get a true or false statement. Since –3 ≥ 5 is always false we know we want the two outside inequalities, rather than their intersection.

Example Question #796 : Psat Mathematics

If x+1< 4 and y-2<-1 , then which of the following could be the value of ?

Possible Answers:

Correct answer:

Explanation:

To solve this problem, add the two equations together:

x+1<4

y-2<-1

x+1+y-2<4-1

x+y-1<3

x+y<4

The only answer choice that satisfies this equation is 0, because 0 is less than 4.

Example Question #141 : Algebra

If , which of the following could be a value of ?

Possible Answers:

-

Correct answer:

Explanation:

In order to solve this inequality, you must isolate  on one side of the equation. 

Therefore, the only option that solves the inequality is

 

Example Question #21 : Inequalities

What values of  make the statement  true?

Possible Answers:

Correct answer:

Explanation:

First, solve the inequality :

Since we are dealing with absolute value,  must also be true; therefore:

Example Question #797 : Psat Mathematics

If –1 < n < 1, all of the following could be true EXCEPT:

Possible Answers:

n2 < n

16n2 - 1 = 0

n2 < 2n

(n-1)2 > n

|n2 - 1| > 1

Correct answer:

|n2 - 1| > 1

Explanation:

N_part_1

N_part_2

N_part_3

N_part_4

N_part_5

Example Question #798 : Psat Mathematics

(√(8) / -x ) <  2. Which of the following values could be x?

Possible Answers:

-1

-2

-4

-3

All of the answers choices are valid.

Correct answer:

-1

Explanation:

The equation simplifies to x > -1.41. -1 is the answer.

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