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.

[EX Q]: 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 %
[EX A]: a

[EX Q]: Problem: students at a school were on average 180 cm tall. the average female height was 170 cm, and the average male height was 182 cms. what was the ratio of men to women ?
Options: a. 5: 2, b. 5: 1, c. 4: 3, d. 4: 1, e. 3: 1
[EX A]: b

[EX Q]: Problem: a train travels from new york to chicago, a distance of approximately 540 miles, at an average rate of 60 miles per hour and arrives in chicago at 6: 00 in evening, chicago time. at what hour in the morning, new york time, did the train depart for chicago ? ( note: chicago time is one hour earlier than new york time.
Options: a. 3: 00, b. 4: 00, c. 5: 00, d. 6: 00, e. 10: 00
[EX A]:
e