A clock becomes 20 minutes fast every day. If it is made correct at 12 O' clock at noon, then what time will it show at 6 O' clock in the morning?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 6 : 15
A clock that gains at a steady rate gains in proportion to the time that has passed. It was set right at noon, so its gain starts from zero then.
Gain per hour: 20 minutes in 24 hours \(\displaystyle=\frac{20}{24}=\frac{5}{6}\) minute an hour
From 12 noon to 6 o’clock the next morning: 18 hours
Gain in 18 hours: \(\displaystyle18\times\frac{5}{6}=15\) minutes
The clock is 15 minutes ahead, so it shows 6 : 15