Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
--------
Question: Problem: the present worth of rs. 2310 due years hence, the rate of interest being 15 % per annum, is :
Options: a. rs. 1440, b. rs. 1750, c. rs. 1680, d. rs. 1840, e. none of these

Answer: c

Question: Problem: in one alloy there is 10 % chromium while in another alloy it is 6 %. 15 kg of the first alloy was melted together with 35 kg of the second one to form a third alloy. find the percentage of chromium in the new alloy.
Options: a. 7.2 %, b. 9 %, c. 9.2 %, d. 8.6 %, e. 8.4 %

Answer: a

Question: Problem: three pipes a, b and c can fill a tank from empty to full in 30 minutes, 20 minutes and 10 minutes respectively. when the tank is empty, all the three pipes are opened. a, b and c discharge chemical solutions p, q and r respectively. what is the proportion of solution p in the liquid in the tank after 3 minutes ?
Options: a. 3 / 11, b. 2 / 11, c. 1 / 11, d. 4 / 11, e. 1 / 11

Answer:
b