PSAT Math : Arithmetic

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Find The Part From The Whole

A pitcher is currently \dpi{80} \frac{4}{5} of the way full of water.  If \dpi{80} 3 ounces are poured out, then the pitcher would be  of the way full.  How many ounces of water are in the pitcher before the \dpi{80} 3 ounces are poured out?

Possible Answers:

Correct answer:

Explanation:

Let p represent the total capacity of the pitcher.  The current volume in the pitcher is \dpi{80} \frac{4}{5}p.  If this volume is depleted by \dpi{80} 3 ounces, it becomes \dpi{80} \frac{3}{4}p.  In other words:

\dpi{80} \frac{4}{5}p - 3 = \frac{3}{4}p

Solve this equation for \dpi{80} p and get:

\dpi{80} \frac{4}{5}p-\frac{3}{4}p=3

\dpi{80} \frac{16}{20}p-\frac{15}{20}p=3

\dpi{80} \frac{1}{20}p=3

\dpi{80} p=60

Remember, \dpi{80} p represents the total capacity of the pitcher, or 60 ounces.  The question asks how many ounces are in the pitcher at the beginning of the problem, so evaluate\dpi{80} \frac{4}{5}p=\frac{4}{5}\times 60=48.

Example Question #1 : Operations With Fractions

Define an operation  as follows:

For all real ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Example Question #2 : How To Subtract Fractions

Define an operation  as follows:

For all real ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Example Question #3 : How To Subtract Fractions

Define an operation  as follows:

For all real ,

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Example Question #4 : Operations With Fractions

Define an operation  as follows:

For all real ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

 

Example Question #2 : Operations With Fractions

Define an operation  as follows:

For all real ,

Evaluate 

Possible Answers:

Correct answer:

Explanation:

Example Question #1 : Operations With Fractions

Define an operation  as follows:

For all real ,

.

Evaluate .

Possible Answers:

The correct answer is not among the other responses.

Correct answer:

The correct answer is not among the other responses.

Explanation:

This answer is not among the choices given.

Example Question #1661 : Psat Mathematics

Subtract and simplify the fractions:

Possible Answers:

Correct answer:

Explanation:

First we need to give them common denominators. Remember, whatever you do to the denominator you must do to the numerator:

From here, we do algebraic operations to subtract and simplify.

Example Question #1 : How To Divide Fractions

Simplify:

  Sat_math_167_03

 

 

Possible Answers:

a2/c2

a/b/c/d

ac/bd

ad/bc

It is already in simplest terms

Correct answer:

ad/bc

Explanation:

Division is the same as multiplying by the reciprocal.  Thus, a/b ÷ c/d = a/b x d/c = ad/bc

 

 

Example Question #2 : How To Divide Fractions

If p is a positive integer, and 4 is the remainder when p-8 is divided by 5, which of the following could be the value of p?

Possible Answers:

17

20

19

18

Correct answer:

17

Explanation:

Remember that if x has a remainder of 4 when divided by 5, x minus 4 must be divisible by 5. We are therefore looking for a number p such that p - 8 - 4 is divisible by 5. The only answer choice that fits this description is 17. 

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