Question

A typist types $$70$$ pages in $$3$$ hours $$30$$ minutes. How long will she take to type $$300$$ pages?

Answer 1

A typist types $$70$$ pages in $$3$$ hours $$30$$ minutes
$$3$$ hours $$30$$ minutes $$=3 \dfrac{30}{60}$$ hours
$$=3\dfrac 12=\dfrac 72$$ hours
Let she will type $$300$$ pages $$=x$$ hours
$$\therefore 70:300=\dfrac 72 :x$$ $$(ad=bc)$$
$$70\times x=\dfrac{300 \times 7}{2}\Rightarrow x=\dfrac{300 \times 7}{70\times 2}=15$$
$$\therefore$$ He will type in $$15$$ hours.