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.

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 %
a

Problem: if the price of a certain computer increased 30 percent from b dollars to 351 dollars, then 2 b =
Options: a. 540, b. 570, c. 619, d. 649, e. 700
a

Problem: in a certain lottery, the probability that a number between 1 and 15, inclusive, is drawn is 1 / 3. if the probability that a number 1 or larger is drawn is 2 / 3, what is the probability that a number less than or equal to 15 is drawn ?
Options: a. 2 / 3, b. 1 / 3, c. 1 / 4, d. 1 / 6, e. 2 / 5
a