The ratio of number of girls to boys in a school of 2520 students is 27:29. How many more girls should be admitted to make the ratio 1:1?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

First, calculate the current number of girls and boys. The total ratio parts are 27 + 29 = 56. With 2520 students, each part represents 2520 / 56 = 45 students.
The current number of girls is 27 parts × 45 students/part = 1215. The current number of boys is 29 parts × 45 students/part = 1305.
To achieve a 1:1 ratio, the number of girls must equal the number of boys. The target number of girls is therefore 1305.
The number of additional girls needed is the difference between the target number of girls and the current number: 1305 - 1215 = 90.

Option B: Adding 86 girls would result in a total of 1215 + 86 = 1301 girls, which is not equal to the 1305 boys.
Option C: Adding 92 girls would result in a total of 1215 + 92 = 1307 girls. This number exceeds the number of boys, so the ratio would not be 1:1.
Option D: Adding 88 girls would result in a total of 1215 + 88 = 1303 girls, which is not equal to the 1305 boys.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Solving problems involving ratio and proportion as background academic context rather than a clinical decision trigger.
This question assesses basic mathematical and logical reasoning skills, which are foundational for various calculations in nursing, such as medication dosage, IV drip rates, and interpreting patient data.
While not a direct clinical scenario, the ability to perform multi-step calculations accurately is a critical safety skill for nurses to prevent errors.
What if the question asked to remove boys to make the ratio 1:1? The number of boys would need to be reduced to match the number of girls (1215). The number of boys to be removed would be 1305 - 1215 = 90.

How to Approach the Question

First, identify the given information: total students (2520), the ratio of girls to boys (27:29), and the target ratio (1:1).
Calculate the total number of parts in the initial ratio by adding the individual parts (27 + 29 = 56).
Determine the value of one 'part' by dividing the total number of students by the total parts (2520 / 56).
Use the value of one part to calculate the current number of girls and boys.
Determine the difference between the number of boys and girls. This difference is the number of girls that need to be added to achieve a 1:1 ratio.
Select the option that matches your calculated result.

Concept Tested & Keywords

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