instruction:
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: two trains, one from howrah to patna and the other from patna to howrah, start simultaneously. after they meet, the trains reach their destinations after 10 hours and 8 hours respectively. the ratio of their speeds is
Options: a. 4: 9, b. 4: 3, c. 4: 12, d. 4: 8, e. 4: 5
answer:
e

question:
Problem: a man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. the ratio of the speed of the boat in still water and stream is
Options: a. 3: 1, b. 1: 3, c. 2: 4, d. 4: 2, e. none of these
answer:
a

question:
Problem: seed mixture x is 40 percent ryegrass and 60 percent bluegrass by weight; seed mixture y is 25 percent ryegrass and 75 percent fescue. if a mixture of x and y contains 40 percent ryegrass, what percent of the weight of this mixture is x ?
Options: a. 100 %, b. 33.33 %, c. 40 %, d. 50 %, e. 66.66 %
answer:
a