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: he average of 10 numbers is 23. if each number is increased by 4, what will the new average be ?
Options: a. 26, b. 27, c. 88, d. 99, e. 12

Answer: b


Question: Problem: a train 510 m long is running at a speed of 45 km / hr. in what time will it pass a bridge 140 m long ?
Options: a. 40, b. 52, c. 26, d. 21, e. 14

Answer: b


Question: Problem: a dog is tied to a tree by a long nylon cord. if the dog runs from the due north side of the tree to the due south side of the tree with the cord extended to its full length at all items, and the dog ran approximately 30 feet, what was the approximate length of the nylon cord, in feet ?
Options: a. 30, b. 25, c. 15, d. 10, e. 5

Answer:
d