If 75 % of a class answered the first question on a certain test correctly, 55…
2024
If 75 % of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percentage answered both correctly
- A.
100%
- B.
199%
- C.
50%
- D.
225%
Attempted by 2427 students.
Show answer & explanation
Correct answer: C
Solution: Find the percentage who answered both questions correctly.
Assume 100 students to work with percentages directly.
Given 20% answered neither, so 100 - 20 = 80 students answered at least one question correctly.
Use the inclusion–exclusion formula: number who answered at least one = number who answered first + number who answered second - number who answered both.
Substitute the values: 80 = 75 + 55 - (both). Solve for both: both = 75 + 55 - 80 = 50.
Answer: 50%