Question:

How many girls are there in the class? Statement (I): There are 90 students in the class. Statement (II): The ratio of boys to girls is \(7:8\).

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To divide a quantity according to a ratio, first find the total number of ratio parts and then calculate the value of one part.
Updated On: Jun 12, 2026
  • Statement I alone is sufficient, but Statement II alone is not sufficient.
  • Statement II alone is sufficient, but Statement I alone is not sufficient.
  • Both statements together are sufficient, but neither statement alone is sufficient.
  • Even both statements together are not sufficient.
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The Correct Option is C

Solution and Explanation

Concept: When a ratio and a total are known, individual quantities can be found.

Step 1:
Analyze Statement (I). Total students: \[ 90. \] No information regarding distribution between boys and girls. Statement (I) is insufficient.

Step 2:
Analyze Statement (II). Ratio: \[ 7:8. \] Total number is unknown. Possible values: \[ 7,8 \] or \[ 14,16 \] or \[ 21,24. \] Statement (II) is insufficient.

Step 3:
Combine both statements. Ratio sum: \[ 7+8=15. \] One part: \[ \frac{90}{15}=6. \] Girls: \[ 8\times 6=48. \] Hence the number of girls is uniquely determined. Therefore both statements together are sufficient.
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