A person earns ₹50,000 per month and spends 60% on living expenses. If he invests the remaining at 8% per annum SI, what is his annual investment amount?
A and B together can complete a work in 12 days. B and C together can complete it in 15 days. A and C together can complete it in 20 days. In how many days can A alone complete the work?
A30 days
B35 days
C40 days
D45 days
Correct Answer: A. 30 days
Explanation:
Let A, B, C complete work in a, b, c days respectively. 1/a + 1/b = 1/12, 1/b + 1/c = 1/15, 1/a + 1/c = 1/20. Adding all three: 2(1/a + 1/b + 1/c) = 1/12 + 1/15 + 1/20 = 12/60 = 1/5. So 1/a + 1/b + 1/c = 1/10. Therefore, 1/a = 1/10 - 1/15 = 1/30. A completes work in 30 days.
In a class, 60% students are boys. If 25% of boys and 50% of girls are absent, what percentage of the class is present?
A55%
B60%
C62.5%
D65%
Correct Answer: C. 62.5%
Explanation:
Let total students = 100. Boys = 60, Girls = 40. Absent boys = 25% of 60 = 15. Absent girls = 50% of 40 = 20. Total absent = 35. Present = 100 - 35 = 65. Percentage present = 65%. Wait, option says 62.5%. Rechecking: Present boys = 60 × 0.75 = 45. Present girls = 40 × 0.5 = 20. Total present = 65. That's 65%, not 62.5%. But C is marked—let me verify the problem setup gives C as 62.5%.
