A student scores 92% in an examination. His scores were 89, 99, 88, 92 in 4 subjects. Find his score in the 5th subject.

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

The problem requires finding a missing value in a set of numbers when the average (mean) is known.
First, calculate the total sum of scores needed for all 5 subjects to average 92: Total Sum = Mean × Number of Subjects = 92 × 5 = 460.
Next, sum the scores of the 4 known subjects: 89 + 99 + 88 + 92 = 368.
The score of the 5th subject is the difference between the total sum and the sum of the known scores: 460 - 368 = 92.

Option A: If the score were 94, the total sum would be 368 + 94 = 462. The average would be 462 / 5 = 92.4, which is not the required average of 92.
Option B: If the score were 96, the total sum would be 368 + 96 = 464. The average would be 464 / 5 = 92.8, which is not the required average of 92.
Option D: If the score were 100, the total sum would be 368 + 100 = 468. The average would be 468 / 5 = 93.6, which is not the required average of 92.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculating a missing value in a data set given the mean as background academic context rather than a clinical decision trigger.
Understanding how to calculate averages and work with missing data is a fundamental mathematical skill tested in the aptitude section of nursing entrance exams.
This type of problem-solving is analogous to clinical calculations, such as determining a patient's average fluid intake over a shift when one measurement is missing but the total is known.
What if? If the student's average score was 90% instead of 92%, the total required score would be 90 × 5 = 450. The fifth subject's score would then be 450 - 368 = 82.

How to Approach the Question

Identify the key information given: the number of items (5 subjects), the mean (92%), and the values of some of the items (four scores).
Recall the formula for the mean (average): Mean = Total Sum / Number of Items.
Rearrange the formula to find the total sum: Total Sum = Mean × Number of Items.
Calculate the sum of the known values.
Subtract the sum of the known values from the total sum to find the missing value.
Check your answer by calculating the mean with the value you found to ensure it matches the given mean.

Concept Tested & Keywords

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Practise the full DSSSB - 29 August 2019 (Shift-1)

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