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.

[Q]: Problem: a bag contains 10 green and 8 white balls. if two balls are drawn simultaneously, the probability that both are of the same colour is
Options: a. 8 / 15, b. 21 / 44, c. 3 / 5, d. 11 / 15, e. 7 / 15
[A]: b


[Q]: Problem: raman mixed 48 kg of butter at rs. 150 per kg with 36 kg butter at the rate of rs. 125 per kg. at what price per kg should he sell the mixture to make a profit of 40 % in the transaction ?
Options: a. 129, b. 287, c. 195, d. 188, e. 112
[A]: c


[Q]: Problem: two pipes a and b can separately fill a cistern in 60 minutes and 75 minutes respectively. there is a third pipe in the bottom of the cistern to empty it. if all the three pipes are simultaneously opened, then the cistern is full in 50 minutes. in how much time, the third pipe alone can empty the cistern ?
Options: a. 90 min, b. 100 min, c. 110 min, d. 120 min, e. 130 min
[A]:
b