Difficulty: Medium
Correct Answer: 22
Explanation:
Introduction / Context:
This question is a typical linear equation word problem involving prices of two different types of textbooks. It tests basic algebra skills in setting up equations from real-life style statements. We are given a relationship between the cost of a mathematics textbook and a literature textbook, and also a comparison between the total costs of multiple copies of each. The goal is to find the price of one literature textbook using these relationships.
Given Data / Assumptions:
Concept / Approach:
We express both total costs in terms of L, then use the given difference of 38 rupees between these totals to form a linear equation. Specifically, the cost of 5 literature textbooks is 5L, and the cost of 3 mathematics textbooks is 3(L + 2). Given that 5L is 38 more than the latter, we write 5L = 3(L + 2) + 38. Solving this equation gives the price of one literature textbook. This approach is standard for word problems involving comparative costs.
Step-by-Step Solution:
Step 1: Let the cost of one literature textbook be L rupees.
Step 2: Then the cost of one mathematics textbook is L + 2 rupees.
Step 3: The total cost of 5 literature textbooks is 5L.
Step 4: The total cost of 3 mathematics textbooks is 3(L + 2).
Step 5: According to the problem, 5 literature textbooks cost Rs 38 more than 3 mathematics textbooks.
Step 6: Form the equation: 5L = 3(L + 2) + 38.
Step 7: Expand the right side: 3(L + 2) = 3L + 6, so the equation becomes 5L = 3L + 6 + 38.
Step 8: Simplify: 5L = 3L + 44.
Step 9: Subtract 3L from both sides: 2L = 44.
Step 10: Divide both sides by 2: L = 22.
Step 11: Therefore, one literature textbook costs Rs 22.
Verification / Alternative check:
Check using L = 22. Then one mathematics textbook costs 22 + 2 = 24 rupees. The cost of 5 literature textbooks is 5 * 22 = 110 rupees. The cost of 3 mathematics textbooks is 3 * 24 = 72 rupees. The difference is 110 − 72 = 38 rupees, which matches the given condition. This confirms that the cost of one literature textbook is correctly found as 22 rupees.
Why Other Options Are Wrong:
Option (a) 44: If literature cost were 44, numbers would not satisfy the given 38 rupee difference.
Option (c) 24: This would make mathematics textbooks cost 26, and totals would not differ by 38.
Option (d) 11: This would produce totals that differ by much less than 38 rupees.
Common Pitfalls:
Common mistakes include reversing the relationship (for example, assuming mathematics is cheaper than literature), misinterpreting the phrase "cost 38 rupees more," or forgetting to add 2 correctly when computing mathematics textbooks costs. Being careful with the language and assigning variables clearly helps prevent these issues.
Final Answer:
The cost of one literature textbook is Rs 22.
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