7th Grade Math : Operations

Study concepts, example questions & explanations for 7th Grade Math

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Example Questions

Example Question #4 : 7th Grade Math

Andrew spends every Saturday at the gym working out. He can complete \(\displaystyle \frac{1}{12}\) of his workout in \(\displaystyle \frac{1}{6}\) of an hour. If he continues at this rate, how much of his workout does Andrew complete per hour?  

Possible Answers:

\(\displaystyle \frac{1}{2}\textup{ of his workout}\)

\(\displaystyle \frac{1}{6}\textup{ of his workout}\)

\(\displaystyle \frac{1}{3}\textup{ of his workout}\)

\(\displaystyle \frac{1}{4}\textup{ of his workout}\)

Correct answer:

\(\displaystyle \frac{1}{2}\textup{ of his workout}\)

Explanation:

The phrase "per hour" gives us a clue that we are going to divide. In this problem, we can replace the word "per" with a division sign; therefore, we will have the portion of his workout, \(\displaystyle \frac{1}{12}\), divided by hours, \(\displaystyle \frac{1}{6}\):

\(\displaystyle \frac{\ \frac{1}{12}\ \textup{of a workout}}{\ \frac{1}{6}\ \textup{hours}}\)

Remember that when we divide fractions, we can simply multiply by the reciprocal of the denominator to solve. 

\(\displaystyle \frac{1}{6}\rightarrow \frac{6}{1}\)

Therefore:

\(\displaystyle \frac{1}{12}\times\frac{6}{1}=\frac{6}{12}=\frac{1}{2}\)

Andrew can complete \(\displaystyle \frac{1}{2}\) of his workout per hour. 

Example Question #1 : Operations

Solve:

\(\displaystyle -12+4\)

Possible Answers:

\(\displaystyle -4\)

\(\displaystyle 4\)

\(\displaystyle -8\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle -8\)

Explanation:

In order to solve this problem, we need to start at \(\displaystyle -12\) on the number line. 

 12

Next, we have \(\displaystyle +4\) which means we need to move \(\displaystyle 4\) places to the right on the number line. When we have an addition sign  \(\displaystyle (+)\) we move to the right because that is towards the positive side of the number line. When we have a subtraction sign \(\displaystyle (-)\) we move to the left because that is towards the negative side of the number line. 

  8

The orange arrow moved \(\displaystyle 4\) places to the right, and ended at \(\displaystyle -8\); thus,

\(\displaystyle -12+4=-8\)

Example Question #2 : Operations

Solve: 

\(\displaystyle -35\div-5\)

Possible Answers:

\(\displaystyle -40\)

\(\displaystyle 40\)

\(\displaystyle 7\)

\(\displaystyle -7\)

Correct answer:

\(\displaystyle 7\)

Explanation:

We know the following information:

\(\displaystyle 35\div5=7\)

In this particular case, do the negative numbers change our answer? . There are a couple of rules that we need to remember when multiplying with negative numbers:

  • A negative number divided by a positive number will always equal a negative number, and a positive number divided by a negative number will always equal a negative number.
  • A negative number divided by a negative number will always equal a positive number 

Thus,

\(\displaystyle -35\div-5=7\)

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