issb mathematics MCQ #678

A alone 15 days, B alone 45 days. Together?

issb mathematics MCQ #678

Question 1
Q1. A alone 15 days, B alone 45 days. Together?
- A) 10 days
- B) 11 days
- C) 11.25 days
- D) 12 days
Answer: 11.25 days
Explanation: Rates 1/15 plus 1/45 equals 4/45 so about 11.25 days. Work each step carefully; ISSB math rewards accuracy under time pressure.