Basic Arithmetic : Operations with Fractions

Study concepts, example questions & explanations for Basic Arithmetic

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Example Questions

Example Question #1 : Multiplication With Fractions

Multiply:

\(\displaystyle \frac{5}{6}\times\frac{12}{25}=?\)

Possible Answers:

\(\displaystyle 2\)

\(\displaystyle \frac{60}{100}\)

\(\displaystyle \frac{2}{5}\)

\(\displaystyle \frac{1}{75}\)

Correct answer:

\(\displaystyle \frac{2}{5}\)

Explanation:

Multiply the numerators together, then multiply the denominators together.

\(\displaystyle \frac{5}{6}\times\frac{12}{25}=\frac{5 \times 12}{6\times25}=\frac{60}{150}\)

To simplfy we can pull out a \(\displaystyle 30\) from the numerator and denominator, thus canceling them. The following answer is the result:

\(\displaystyle =\frac{30\cdot2}{30\cdot5}=\frac{2}{5}\)

Example Question #2 : Multiplication With Fractions

In a classroom of 36, \(\displaystyle \frac{1}{3}\) of the students are girls. If \(\displaystyle \frac{1}{6}\) of the girls enjoy eating strawberries, and \(\displaystyle \frac{1}{3}\) of the boys also enjoy eating strawberries, how many total students in the class enjoy eating strawberries?

Possible Answers:

\(\displaystyle 9\)

\(\displaystyle 10\)

\(\displaystyle 12\)

\(\displaystyle 6\)

Correct answer:

\(\displaystyle 10\)

Explanation:

First, find out how many girls and boys are in the class.

Multiply 36 by \(\displaystyle \frac{1}{3}\) to find the number of girls.

\(\displaystyle 36\times \frac{1}{3}=12\)

Then, subtract the number of girls from the total number of students in the class to find the number of boys.

\(\displaystyle 36-12=24\)

Now, we can figure out how many girls enjoy eating strawberries. Multiply the total number of girls by the fraction of girls who enjoy eating strawberries.

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

Now, do the same with the boys.

\(\displaystyle 24\times\frac{1}{3}=8\)

Add these two numbers together to get the total number of students who enjoy eating strawberries.

\(\displaystyle 2+8=10\)

Example Question #3 : Multiplication With Fractions

Solve and simplify. 

\(\displaystyle \frac{3}{4} \times \frac{4}{6}\)

Possible Answers:

\(\displaystyle \frac{7}{24}\)

\(\displaystyle \frac{1}{2}\)

\(\displaystyle \frac{7}{10}\)

\(\displaystyle \frac{12}{10}\)

\(\displaystyle \frac{1}{4}\)

Correct answer:

\(\displaystyle \frac{1}{2}\)

Explanation:

When multiplying fractions, you simply multiply the numerators and then multiply the denominators. Then simplify the fraction.

\(\displaystyle \frac{3}{4} \times \frac{4}{6}=\frac{3\cdot 4}{4 \cdot 6}\)

\(\displaystyle =\frac{12}{24}=\frac{1\cdot 12}{2 \cdot 12}=\frac{1}{2}\)

(Note: by dividing both our numerator and our denominator by \(\displaystyle 12\), gives us our final answer of \(\displaystyle \frac{1}{2}\).

Example Question #4 : Multiplication With Fractions

Evaluate the following:

 \(\displaystyle -\frac{4}{5}\cdot\left ( \frac{1}{2} \right )^{2}\)

Possible Answers:

\(\displaystyle -5\)

\(\displaystyle -\frac{11}{20}\)

\(\displaystyle -\frac{1}{5}\)

\(\displaystyle -\frac{16}{5}\)

\(\displaystyle -\frac{17}{20}\)

Correct answer:

\(\displaystyle -\frac{1}{5}\)

Explanation:

This problem involves order of operations.  

The correct order is:  Parenthesis, Exponents, Multiplication, Division, Addition, and Subtraction.  

Rewrite the exponent and cancel out the 4 on the numerator and denominator.

\(\displaystyle -\frac{4}{5}\cdot\frac{1}{4}= -\frac{1}{5}\)

 

Example Question #5 : Fractions

Please choose the best answer for the question below. 

\(\displaystyle \frac{1}{2} \times\frac{36}{55}=\) 

Possible Answers:

\(\displaystyle 36/22\)

\(\displaystyle 36/115\)

\(\displaystyle 9/25\)

\(\displaystyle 18/55\)

\(\displaystyle 36/105\)

Correct answer:

\(\displaystyle 18/55\)

Explanation:

To do this problem, simply multiply through (i.e. numerator by numerator and denominator by denominator):

\(\displaystyle 1/2 \cdot 36/55 = 36/110\)

And then reduce to find your answer--both \(\displaystyle 36\) and \(\displaystyle 110\) are divisible by two.

\(\displaystyle 36/110 = 18/55\)

Example Question #2 : Fractions

Multiply these fractions:

\(\displaystyle \frac{7}{9}*\frac{1}{14}\)

Possible Answers:

\(\displaystyle \frac{1}{9}\)

\(\displaystyle \frac{2}{9}\)

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

\(\displaystyle \frac{1}{18}\)

Correct answer:

\(\displaystyle \frac{1}{18}\)

Explanation:

When multiplying fractions, all we have to do is multiply the numerators together and multiply the denominators together:

\(\displaystyle \frac{7}{9}*\frac{1}{14}=\frac{7*1}{9*14}=\frac{7}{126}\)

Simply the fraction to get the final answer:

\(\displaystyle \frac{7}{126}\div \frac{7}{7}=\frac{1}{18}\)

Example Question #6 : Fractions

Multiply these fractions:

\(\displaystyle \frac{5}{12}*\frac{3}{7}\)

Possible Answers:

\(\displaystyle \frac{5}{28}\)

\(\displaystyle \frac{1}{4}\)

\(\displaystyle \frac{3}{14}\)

\(\displaystyle \frac{5}{27}\)

Correct answer:

\(\displaystyle \frac{5}{28}\)

Explanation:

When multiplying fractions, all we have to do is multiply the numerators together and multiply the denominators together:

\(\displaystyle \frac{5}{12}*\frac{3}{7}=\frac{5*3}{12*7}=\frac{15}{84}\)

Simply the fraction to get the final answer:

\(\displaystyle \frac{15}{84}\div \frac{3}{3}=\frac{5}{28}\)

Example Question #2 : Multiplication With Fractions

Multiply these fractions:

\(\displaystyle \frac{2}{3}*\frac{5}{6}\)

Possible Answers:

\(\displaystyle \frac{5}{9}\)

\(\displaystyle \frac{4}{9}\)

\(\displaystyle \frac{2}{9}\)

\(\displaystyle \frac{7}{9}\)

Correct answer:

\(\displaystyle \frac{5}{9}\)

Explanation:

When multiplying fractions, all we have to do is multiply the numerators together and multiply the denominators together:

\(\displaystyle \frac{2}{3}*\frac{5}{6}=\frac{2*5}{3*6}=\frac{10}{18}\)

Simply the fraction to get the final answer:

\(\displaystyle \frac{10}{18}\div \frac{2}{2}=\frac{5}{9}\)

Example Question #191 : Basic Arithmetic

Multiply these fractions:

\(\displaystyle \frac{1}{2}*\frac{2}{3}\)

Possible Answers:

\(\displaystyle 1\frac{1}{2}\)

\(\displaystyle \frac{1}{3}\)

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

\(\displaystyle 1\frac{1}{3}\)

Correct answer:

\(\displaystyle \frac{1}{3}\)

Explanation:

When multiplying fractions, all we have to do is multiply the numerators together and multiply the denominators together:

\(\displaystyle \frac{1}{2}*\frac{2}{3}=\frac{1*2}{2*3}=\frac{2}{6}\)

Simply the fraction to get the final answer:

\(\displaystyle \frac{2}{6}\div \frac{2}{2}=\frac{1}{3}\)

Example Question #3 : Fractions

Multiply these fractions:

\(\displaystyle \frac{5}{7}*\frac{1}{3}\)

Possible Answers:

\(\displaystyle \frac{6}{21}\)

\(\displaystyle \frac{4}{21}\)

\(\displaystyle \frac{1}{3}\)

\(\displaystyle \frac{5}{21}\)

Correct answer:

\(\displaystyle \frac{5}{21}\)

Explanation:

When multiplying fractions, all we have to do is multiply the numerators together and multiply the denominators together:

\(\displaystyle \frac{5}{7}*\frac{1}{3}=\frac{5*1}{7*3}=\frac{5}{21}\)

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