Chapter 3: Problem 7
Multiply. Write a mixed numeral for the answer. $$ 3 \frac{2}{5} \cdot 2 \frac{7}{8} $$
Short Answer
Expert verified
9 \(\frac{31}{40}\)
Step by step solution
01
Convert Mixed Numbers to Improper Fractions
First, convert the mixed numbers to improper fractions. For 3 \(\frac{2}{5}\), multiply the whole number 3 by the denominator 5 and add the numerator 2: \[ 3 \frac{2}{5} = \frac{3 \times 5 + 2}{5} = \frac{15 + 2}{5} = \frac{17}{5} \] For 2 \(\frac{7}{8}\), multiply the whole number 2 by the denominator 8 and add the numerator 7: \[ 2 \frac{7}{8} = \frac{2 \times 8 + 7}{8} = \frac{16 + 7}{8} = \frac{23}{8} \]
02
Multiply the Improper Fractions
Multiply the numerators together and the denominators together: \[ \frac{17}{5} \times \frac{23}{8} = \frac{17 \times 23}{5 \times 8} = \frac{391}{40} \]
03
Convert the Improper Fraction to a Mixed Number
Convert \(\frac{391}{40}\) to a mixed number by dividing 391 by 40. The quotient is the whole number part, and the remainder over the original denominator is the fractional part: \[ 391 ÷ 40 = 9 \text{ remainder } 31 \] So \(\frac{391}{40} = 9 \frac{31}{40} \)
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Converting Mixed Numbers to Improper Fractions
Mixed numbers are numbers that combine a whole number and a fraction. To multiply mixed numbers, we first need to convert them into improper fractions. An improper fraction has a numerator larger than its denominator.
Here's how to convert a mixed number into an improper fraction:
\[\frac{3 \times 5 + 2}{5} = \frac{17}{5} \] Similarly, for 2 \frac{7}{8}, multiply 2 by 8 and add 7, then place the result over 8:
\[\frac{2 \times 8 + 7}{8} = \frac{23}{8}\]
Here's how to convert a mixed number into an improper fraction:
- Multiply the whole number by the denominator of the fraction part.
- Add the result to the numerator of the fraction part.
- Place the sum over the original denominator.
\[\frac{3 \times 5 + 2}{5} = \frac{17}{5} \] Similarly, for 2 \frac{7}{8}, multiply 2 by 8 and add 7, then place the result over 8:
\[\frac{2 \times 8 + 7}{8} = \frac{23}{8}\]
Multiplying Fractions
Once mixed numbers are converted to improper fractions, we can easily multiply them. Here's how:
For example, if we have the fractions \frac{17}{5} and \frac{23}{8}, we multiply the numerators (17 and 23) and the denominators (5 and 8) like this:
\[\frac{17}{5} \times \frac{23}{8} = \frac{17 \times 23}{5 \times 8} = \frac{391}{40} \] Ensure to multiply straight across - numerator with numerator and denominator with denominator. The result here is \frac{391}{40}\.
- Multiply the numerators (the top numbers of the fractions) together to get the new numerator.
- Multiply the denominators (the bottom numbers of the fractions) together to get the new denominator.
For example, if we have the fractions \frac{17}{5} and \frac{23}{8}, we multiply the numerators (17 and 23) and the denominators (5 and 8) like this:
\[\frac{17}{5} \times \frac{23}{8} = \frac{17 \times 23}{5 \times 8} = \frac{391}{40} \] Ensure to multiply straight across - numerator with numerator and denominator with denominator. The result here is \frac{391}{40}\.
Converting Improper Fractions to Mixed Numbers
After obtaining the product of the fractions, it usually needs to be converted back into a mixed number. This involves:
For example, to convert \frac{391}{40} into a mixed number, divide 391 by 40:
\[391 \div 40 = 9 \text{remainder} 31\] So, \frac{391}{40} = 9 \frac{31}{40}\. Here, 9 is the whole number, and \frac{31}{40}\ is the fractional part. Thus, the solution is 9 \frac{31}{40}\. Following these steps ensures accurate conversions and simplifies your final results.
- Dividing the numerator by the denominator to get the quotient. The quotient will be the whole number part of the mixed number.
- The remainder from this division will be the numerator of the fractional part.
- The original denominator remains the same for the fractional part.
For example, to convert \frac{391}{40} into a mixed number, divide 391 by 40:
\[391 \div 40 = 9 \text{remainder} 31\] So, \frac{391}{40} = 9 \frac{31}{40}\. Here, 9 is the whole number, and \frac{31}{40}\ is the fractional part. Thus, the solution is 9 \frac{31}{40}\. Following these steps ensures accurate conversions and simplifies your final results.