Question

Find the fourth proportional to :

(i) 1.5, 4.5 and 3.5

(ii) 3a. $6a^2$ and $2a{b}^2$

Answer 1

i) Let the fourth proportion be $x$

Therefore

$\frac{1.5}{4.5}=\frac{3.5}{x}$

$\to x=\frac{3.5\times 4.5}{1.5}=10.5$

Hence $x=10.5$

ii) Let thefourth proportion be $x$

Therefore

$\frac{3a}{6a^2}=\frac{2a{b}^2}{x}\to x^2=2a{b}^2\times 6a^{2}3a=4a^2{b}^2$

Hence $x=4a^2{b}^2$