Chapter 8.1, Problem 3PSA

a

To determine

To find: The value of x in given proportion.

Answer to Problem 3PSA

The value of x is 4

Explanation of Solution

Given information$\frac{\text{3}}{x}\text{=}\frac{\text{12}}{\text{16}}$ .

Formula used

Cross multiplication method

Calculation

  $\begin{array}{l}\frac{3}{x}=\frac{12}{16}\\ \Rightarrow x\times \text{ 12=3}\times \text{16}\\ \Rightarrow x\text{=}\frac{3\times 16}{12}=4\end{array}$

b

To determine

To find: The value of x in given proportion i.e. $\frac{x}{18}=\frac{3}{7}$

Answer to Problem 3PSA

The value of x is $\frac{54}{7}=7\frac{5}{7}$

Explanation of Solution

Given information$\frac{x}{18}=\frac{3}{7}$ .

Formula used Product of means = Product of extremes

Calculation

  $\begin{array}{l}\frac{x}{18}=\frac{3}{7}\\ \Rightarrow x:18::3:7\\ \Rightarrow x\times \text{7=18}\times \text{3}\\ \Rightarrow x\text{=}\frac{3\times 18}{7}=\frac{54}{7}=7\frac{5}{7}\end{array}$ .

c

To determine

To find:The value of x in given proportion i.e. $\frac{\text{7}}{x\text{-4}}=\frac{3}{5}$

Answer to Problem 3PSA

The value of x is $15\frac{2}{3}$

Explanation of Solution

Given information$\frac{\text{7}}{x\text{-4}}=\frac{3}{5}$ .

Formula used :

Product of means = Product of extremes

Calculation

  $\begin{array}{l}\frac{7}{x-4}=\frac{3}{5}\\ \Rightarrow 7:(x-4)::3:5\\ \Rightarrow 3\left(x-4\right)=7\times 5\\ \Rightarrow 3x-12=35\\ \Rightarrow 3x=35+12=47\\ \Rightarrow x=\frac{47}{3}=15\frac{2}{3}\end{array}$