Which piece of information given in the alternatives will additionally be required to answer the following question?
Question:
All the students passed in a class and all obtained a unique rank. Sushma got 7th rank and there are 4 boys ahead of her and the 9 girls behind her. What is the total number of students in the class?

Correct option is B

Given Information:

• Sushma got the 7th rank in the class.
• There are 4 boys ahead of Sushma, which means the first 4 students are boys.
• There are 9 girls behind her, which means there are 9 girls ranked from 8th to 16th.

We are tasked with calculating the total number of students in the class.

Step-by-Step Breakdown:

• Sushma is ranked 7th.
• 4 boys are ahead of her, so the first 4 students are boys.
• 9 girls are behind her, so the students ranked 8th to 16th are girls.

This means that we have:

• 4 boys ahead of Sushma.
• 1 Sushma.
• 9 girls behind her.

Thus, there are 4 + 1 + 9 = 14 students based on the information provided, but this is the total number of students in a part of the class (the group around Sushma).

Now, the total number of students in the class includes the boys before Sushma and girls behind her, and we need additional information to fully calculate the total.

Option Analysis:

• A. There are 2 girls ahead of Sushma.
  This information does not add anything significant to directly help calculate the total number of students. The main critical data point is how many boys and girls there are, but this specific detail doesn’t directly help.

• B. The ratio of the number of girls to the number of boys is 2:3.
  This crucial information helps us establish a relationship between the number of girls and boys in the class. We can use this ratio to find the total number of students. The number of girls and boys can be calculated if we assume the total number of students, and knowing the ratio allows us to solve for the total number.

• C. The number of boys is more than the number of girls in the class.
  This is general information and doesn’t give us enough specific detail to calculate the total number of students. It only provides a broad comparison, not an exact relationship like option B does.

• D. A girl ranked first in the class is Rekha.
  While this gives a specific name for the highest rank, it doesn’t provide any new mathematical relationship that helps us determine the total number of students in the class.

Correct Answer:

B. The ratio of the number of girls to the number of boys is 2:3.

This option provides the necessary ratio that allows us to calculate the total number of students in the class based on the number of boys and girls.