Two successive discounts of 10% and 20% are equivalent to a single discount of?

Appeared in: SGPGI Nursing Officer-2024

Explanation

The problem asks for a single discount equivalent to two successive discounts of 10% and 20%.
This can be solved using the formula for successive discounts: d1 + d2 - (d1 * d2 / 100).
Substituting the values: 10 + 20 - (10 * 20 / 100) = 30 - 2 = 28%.
Alternatively, assuming a price of 100, a 10% discount makes it 90. A 20% discount on 90 is 18, making the final price 72. The total discount is 100 - 72 = 28, which is 28%.

Option B: This is an incorrect calculation. It does not follow the standard formula or logical step-by-step method for successive discounts.
Option C: This is an incorrect calculation. It does not align with the correct formula for combining successive discounts.
Option D: This is an incorrect calculation. It is far from the actual equivalent discount.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of successive discounts as background academic context rather than a clinical decision trigger.
While this is a general aptitude question, the underlying skill of calculating percentages is crucial in nursing.
Nurses frequently use percentage calculations for medication dosages, preparing solutions (e.g., a 2% solution), and titrating IV drips.
Understanding successive changes is also relevant when interpreting changes in lab values or patient weight over multiple time points.

How to Approach the Question

Identify that the question is about 'successive discounts', meaning one discount is applied after the other.
Recognize the common mistake: you cannot simply add the percentages (10% + 20% ≠ 30%).
Choose a calculation method. Method A: Assume a simple starting price like 100.
Calculate the first discount (10% of 100 = 10), find the new price (100 - 10 = 90).
Calculate the second discount on the new price (20% of 90 = 18), find the final price (90 - 18 = 72).
Determine the total discount (100 - 72 = 28) and express it as a percentage (28%).

Concept Tested & Keywords

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Practise the full SGPGI Nursing Officer-2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.