In a test, a candidate attempted only 8 questions and secured 50% marks in each of the questions. If he obtained a total of 40% in the test and all questions in the test carried equal marks, how many questions were there in the test?

Let 'N' be the total number of questions in the test. Let 'M' be the marks allotted for each question. So, the total maximum marks for the test = N * M. The candidate attempted only 8 questions. In each of these 8 questions, he secured 50% marks. Marks obtained in one question = 50% of M = 0.5 * M. Total marks obtained by the candidate = 8 questions * (0.5 * M marks/question) = 4M. The candidate obtained a total of 40% in the test. This means (Total marks obtained) / (Total maximum marks) = 40%. So, (4M) / (N * M) = 0.40. We can cancel 'M' from both the numerator and the denominator: 4 / N = 0.40. Now, solve for N: N = 4 / 0.40 N = 4 / (4/10) N = 4 * (10/4) N = 10. Therefore, there were 10 questions in the test. Analyzing the options: A) 8: If there were 8 questions, and he got 50% in each of the 8, his total score would be 50%, not 40%. This is incorrect. B) 10: This matches our calculated value. If there are 10 questions (total 10M marks) and he scored 4M, his percentage is (4M/10M) * 100 = 40%. This is correct. C) 15: If there were 15 questions (total 15M marks) and he scored 4M, his percentage would be (4M/15M) * 100 = 26.67%, not 40%. This is incorrect. D) 16: If there were 16 questions (total 16M marks) and he scored 4M, his percentage would be (4M/16M) * 100 = 25%, not 40%. This is incorrect. The final answer is B.