Jambmaths question:
If $p:q=\tfrac{2}{3}:\tfrac{5}{6}$and $q:r=\tfrac{3}{4}:\tfrac{1}{2}$ find $p:q:r$
Option A:
9:10:15
Option B:
12:15: 16
Option C:
12:15:10
Option D:
10:15:24
Jamb Maths Solution:
$\begin{align} & p:q=\tfrac{2}{3}:\tfrac{5}{6}\Rightarrow \tfrac{p}{q}=\frac{\tfrac{2}{3}}{\tfrac{5}{6}}=\tfrac{4}{5} \\ & p=\tfrac{4}{5}q-----(i) \\ & q:r=\tfrac{3}{4}:\tfrac{1}{2}\Rightarrow \tfrac{q}{r}=\frac{\tfrac{3}{4}}{\tfrac{1}{2}}=\tfrac{3}{4}\times \tfrac{2}{1}=\tfrac{2}{3} \\ & r=\frac{2}{3}q-----(ii) \\ & \therefore p:q:r=\tfrac{4}{5}q:q:\tfrac{2}{3}q \\ & p:q:r=\tfrac{4}{5}:1:\tfrac{2}{3} \\ & \text{multiply through by 15} \\ & 12p:15q:10r=12:15:10 \\ & \text{option B} \\\end{align}$
Jamb Maths Topic:
Year of Exam: