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: there are 15 boys and 10 girls in a class. if three students are selected at random, in how many ways that 1 girl or 2 boys are selected ?
Options: a. 100, b. 105, c. 115, d. 120, e. 125

Answer: c


Question: 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 %

Answer: a


Question: Problem: the bases of a hemisphere and a cone are equal. if their heights are also equal then ratio between their curved surface area is —
Options: ['a. 1: √ 2', 'b. √ 2 ∶ 1', 'c. 1: 2', 'd. 2: 1', 'e. none of these']

Answer:
b