An outlet pipe can empty 2/3 of a cistern in 12 minutes. In 4 minutes, what part of the cistern will be emptied?
Choices.
A) 1 / 3 B) 2 / 5 C) 2 / 7 D) 2 / 9 E) 3 / 10

Rationale: "4 / 12 * 2 / 3 = 2 / 9 the answer is d ."
Answer: D