Running at the same constant rate, 6 identical machines can produce a total of 270 bottles per minute. At this rate, how many bottles could 10 such machines produce in 4 minutes?

Answer: Option B

Let the required number of bottles be x.
More machines, More bottles (Direct Proportion)
More minutes, More bottles (Direct Proportion)
$$\begin{array}{c}\text{Machines}\text{6}:10\text{hfill}\\ \text{Time(in min}\text{.)}\text{1}:4\text{hfill}\end{array}\}::270:x$$
$$\begin{array}{rl}& \therefore 6\times 1\times x=10\times 4\times 270\\ & \Rightarrow x=\frac{10\times 4\times 270}{6}\\ & \Rightarrow x=1800\end{array}$$