A clock shows 8:21. What time does its mirror image show, the mirror being placed vertically beside the clock?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 3:39
A vertical mirror turns the clock face left to right, so a hand that is some way past 12 on one side appears the same way past 12 on the other side. The two times then add up to 12 hours, so the mirror time is found by subtracting the time from 11:60 (that is, 12:00).
Mirror time \(=\) 11 h 60 min − 8 h 21 min
Minutes: \(60-21=39\)
Hours: \(11-8=3\)
So the mirror image shows 3:39
