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: an aeroplane covers a certain distance at a speed of 150 kmph in 2 hours. to cover the same distance in 1 2 / 3 hours, it must travel at a speed of :
Options: a. 1300 kmph, b. 160 kmph, c. 180 kmph, d. 1080 kmph, e. none
[EX A]: c

[EX Q]: Problem: the probability of two events a and b are 0.25 and 0.40 respectively. the probability that both a and b occur is 0.15. the probability that neither a nor b occur is _________
Options: a. 0.45, b. 0.4, c. 0.5, d. 0.05, e. 0.6
[EX A]: c

[EX Q]: Problem: a alone can do a piece of work in 6 days and b alone in 8 days. a and b undertook to do it for rs. 6000. with the help of c, they completed the work in 3 days. how much is to be paid to c ?
Options: a. s. 375, b. s. 400, c. s. 600, d. s. 750, e. s. 850
[EX A]:
d