A shop sells erasers at ₹8 each and folders at ₹25 each. If a customer buys 5 erasers and 3 folders, what's the total bill?
A₹99
B₹115
C₹105
D₹111
Answer:
B. ₹115
Read Explanation:
Step-by-Step Calculation
- Calculate Eraser Cost: The cost of one eraser is ₹8. For 5 erasers, the total cost is 5 × ₹8 = ₹40.
- Calculate Folder Cost: The cost of one folder is ₹25. For 3 folders, the total cost is 3 × ₹25 = ₹75.
- Calculate Total Bill: Add the two subtotals together: ₹40 (erasers) + ₹75 (folders) = ₹115.
Key Concepts in Arithmetic Problems
- Order of Operations: While this specific problem involves simple multiplication and addition, always ensure you calculate the cost of each item type (multiplication) before summing the total (addition).
- Unitary Method: This problem uses the fundamental unitary method, where the total cost is determined by multiplying the quantity of items by their respective unit prices (Total = Σ (Quantity × Unit Price)).
- Accuracy in Exams: In competitive exams like Kerala PSC, speed and accuracy are crucial. Often, candidates make calculation errors in simple multiplication (e.g., miscalculating 3 × 25). Double-checking subtotals before final summation prevents common errors.