Read the following table carefully and answer the question that follows. The…
2020
Read the following table carefully and answer the question that follows.
The following table embodies the details about the students of the different departments A, B and C in a University for participating in the blood donation camp.
Participation in Blood Donation Camp - Data
* Out of total blood donors.
Ques: If 45 boys from the department 'B' did not donate blood, then the total number of students in the department 'B' is
- A.
120
- B.
150
- C.
80
- D.
200
Show answer & explanation
Correct answer: D
Concept: When a table gives a percentage figure for one subgroup (e.g. "% of donors who are girls") alongside an absolute count for the other subgroup (e.g. "number of boys who donated"), first turn that absolute count into the subgroup total using the given percentage split. Then, to move from a subgroup total (boys) to the department's full strength, use the department's OWN gender-composition percentage (girls % of all students), not the donor-composition percentage — the two percentages describe different populations and must not be mixed.
Working (for department B):
Percentage of blood-donating girls in B is 50%, so boys make up the remaining 50% of B's blood donors.
The 75 boys who donated are that 50% share, so total blood donors in B = 75 ÷ 50% = 150.
Girl donors in B = 150 − 75 = 75.
45 boys in B did not donate, so total boys in B = donors + non-donors = 75 + 45 = 120.
From the table, girls are 40% of ALL students in B (this is a different percentage from the donor split), so boys are the remaining 60% of all students in B.
The 120 boys are that 60% share, so total students in B = 120 ÷ 60% = 200.
Cross-check: Girls in B = 40% of 200 = 80, and boys = 200 − 80 = 120, matching step 4. Donors also check out: 75 boys + 75 girls = 150 total donors, and 75 boys donating is exactly 50% of 150, matching the table.
Answer: Total number of students in department B = 200.