2 persons working 2 hours a day assemble 2 machines in 2 days. The number of machines assembled by 6 persons working 6 hours a day in 6 days is
(a)6
(b)18
(c)27
(d)54
Answer
Answer (as printed): D
Explanation
Let the required number of machines be $x$. More persons, More machines (Direct Proportion). More working hours, More machines (Direct Proportion). More days, More machines (Direct Proportion). Persons $2:6$, Working hours $2:6$, Days $2:6$ :: $2:x$. $\therefore 2 \times 2 \times 2 \times x = 6 \times 6 \times 6 \times 2 \Leftrightarrow x = \frac{6 \times 6 \times 6 \times 2}{2 \times 2 \times 2} = 54$.
Explanation as extracted from the printed page; notation may be imperfect.