Runnning at the same constant rate, 6 identical machines can produce a total of 180 bottles per hour. How many bottles could 15 such machines produce in 30 minutes?
(a)225
(b)250
(c)300
(d)350
Answer
Answer (as printed): A
Explanation
Let the required number of bottles be $x$. More machines, More bottles produced (Direct Proportion) (Direct Proportion) Machines $6: 15: 30\}:: 180: x$ $$\begin{aligned} & \therefore 6 \times 60 \times x=15 \times 30 \times 180 \\ & \Leftrightarrow x=\left(\frac{15 \times 30 \times 180}{6 \times 60}\right)=225 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.