Question

Complete the table if x and y vary directly.

x	3.5	4	7.5	-
y	-	8	-	15

Answer 1

Let the blank spaces be filled with a, b and c.

x	3.5	4	7.5	c
y	a	8	b	15

$\therefore \frac{x_1}{y_1}=\frac{x_2}{y_2}$

$\Rightarrow \frac{3.5}{a}=\frac{4}{8}$

$\Rightarrow 4\times a=3.5\times 8$

$\therefore a=\frac{3.5\times 8}{4}=7$

$\frac{4}{8}=\frac{7.5}{b}$

$\therefore b=\frac{8\times 7.5}{4}=15$

$\frac{4}{8}=\frac{c}{15}$

$\Rightarrow 8\times c=4\times 15$

$\therefore c=\frac{4\times 15}{8}=7.5$

Hence, the required values are a=7, b=15 and c=7.5.