Topic Content:
- Word Problems with Fractions
The quotient of two numbers is the result obtained by dividing one number by another. The quotient of eight divided by four is two.
Worked Example 3.4.1:
Find two-thirds of the sum of 23 and 19.
Solution
\( \frac{2}{3} \: \times \: \scriptsize \left (23 \: + \: 19 \right) \)= \( \frac{2}{3} \: \times \: \frac{42}{1} \)
= \( \scriptsize 2 \: \times \: 14 = 28 \)
Worked Example 3.4.2:
Divide 88 by the sum of 2 and the product of 3 and 3.
Solution
product of 3 and 3
⇒ 3 × 3 = 9
Add 2 to it = \( \scriptsize 2 + (3 \: \times \: 3) \\ \scriptsize = 2 + 9 = 11\)
Divide 88 by the sum which is 11 = \( \frac{88}{11} \\ \scriptsize = 8 \)
Worked Example 3.4.3:
Add the square of 9 to the product of the square roots of 25 and 4, and divide the result by the square root of 100.
Solution
Step 1: square of 9 = 92
Step 2: product of the square roots of 25 and 4 = \( \scriptsize \left(\sqrt{25}\: \times \: \sqrt{4}\right)\)
Step 3: square root of 100 = \( \scriptsize \sqrt{100}\\ = \scriptsize 10 \)
Putting all the steps together and solving the word problem, we get:
\( \frac{9^2 \: + \: \left(\sqrt{25}\: \times \: \sqrt{4}\right)}{\sqrt{100}} \\ = \frac{81 \: + \: \left (5 \: \times \: 2 \right) }{10} \\ = \frac{81 \: + \: 10}{10} \\ = \frac{91}{10} \scriptsize = 9.1\)Worked Example 3.4.4:
Find four-fifths of the difference between the product of 0.25 and 128 and the difference between 32.8 and 25.8
⇒ \( \frac{4}{5} \scriptsize \: \times \: \left(0.25 \: \times \: 128 \right) \: – \: \left(32.8 \: – \: 25.8 \right) \)
⇒ \( \frac{4}{5} \scriptsize \: \times \: 32 \:\: – \: 7 \)
⇒ \( \frac{4}{5} \scriptsize \: \times \: 25 \)
⇒ \( \scriptsize 4 \: \times \: 5 \\ \scriptsize = 20 \)
Worked Example 3.4.5:
Divide the square root of 81 by the difference between the product of -1 and -3 and the square root of 4.
Solution
\( \frac {\sqrt{81}}{(-1 \; \times \: -3) \; – \: \sqrt{4}} \\ = \frac{9}{+3 \: – \: 2}\\ = \frac{9}{1} \\ \scriptsize = 9\)