Question

Given that $24$ carat gold is pure gold, $18$ carat gold is $3/4$ gold and $20$ carat gold is $5/6$ gold. Find the ratio of the pure gold in $18$carat gold to the pure gold in $20$ carat gold.

Answer 1

The ratio of pure gold in 18 carat gold to pure gold in 20 carat gold is:

$\frac{3}{4}:\frac{5}{6}=\frac{3}{4}\ast \frac{6}{5}$

Because whenever a value say 'a' is being divided by some value say 'b' then 'a' can be multiplied by the reciprocal of 'b'.

$\therefore ,\frac{3}{4}\ast \frac{6}{5}=\frac{18}{20}=\frac{9}{10}$