95% of student was present in a school and 18 students were absent. Then the total number of students is?

Appeared in: BSF Staff Nurse - 2015

Explanation

The total percentage of students is 100%. Since 95% of students were present, the percentage of absent students is 100% - 95% = 5%.
The problem states that 18 students were absent, which means this number corresponds to the 5% of absent students.
To find the total number of students (which represents 100%), we can set up a proportion: If 5% is 18, then 100% is 'x'.
Solving the equation (5/100) * Total = 18 gives Total = 18 * (100/5).
Calculating this gives 18 * 20, which equals 360. So, the total number of students is 360.

Option A: This is incorrect. If the total were 500, then 5% absent would mean 25 students were absent (0.05 * 500), not 18.
Option B: This is incorrect. If the total were 450, then 5% absent would mean 22.5 students were absent (0.05 * 450), which is not possible and not equal to 18.
Option C: This is incorrect. If the total were 400, then 5% absent would mean 20 students were absent (0.05 * 400), not 18.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Percentage and Word Problems as background academic context rather than a clinical decision trigger.
This question tests basic mathematical aptitude, a skill necessary for various calculations in nursing, although not directly clinical.
Nurses use percentage calculations for tasks like determining drug dosages, calculating IV drip rates, and interpreting nutritional information.
For example, calculating a percentage weight loss in a patient or understanding the concentration of a solution (e.g., 0.9% saline) relies on the same fundamental math skills.

How to Approach the Question

First, read the question carefully to identify the given values: the percentage of present students (95%) and the absolute number of absent students (18).
Calculate the percentage of absent students. Since the total is 100%, subtract the percentage of present students from 100% (100% - 95% = 5%).
Establish the relationship between the percentage and the number. You now know that 5% of the total student population is equal to 18 students.
Set up an equation to solve for the total (let 'T' be the total). The equation is (5/100) * T = 18.
Solve for T by isolating it: T = 18 * (100/5).
Perform the final calculation (18 * 20) to find the total number of students and select the matching option.

Concept Tested & Keywords

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Practise the full BSF Staff Nurse - 2015

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