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: if 12 machine can finish a job in 40 days, then how many more machines would be needed to finish the job in one - fourth less time ?
Options: a. a. 4, b. b. 8, c. c. 10, d. d. 12, e. e. 16
[EX A]: a

[EX Q]: Problem: the mean of 50 observations is 200. but later he found that there is decrements of 34 from each observations. what is the the updated mean is ?
Options: a. 165, b. 166, c. 190, d. 198, e. 199
[EX A]: b

[EX Q]: Problem: what is 121 times 11 ?
Options: a. 1331, b. 1313, c. 1133, d. 3131, e. 3311
[EX A]:
a