Question

2. A clock is set at 4am. It loses 16 minutes in 24 hours. What will be the correct time when the clock indicates 9pm on the 4th day?

A. 8pm
B. 7pm
C. 10pm
D. 11pm​

Answer 1

$\bold \red{answer}$

10 PM

Time from 4am on a day to 9pm on the 4th day = 89 hours

As per the question, 23 hrs 44 minutes of this clock = 24 hours of the correct clock as this clock loses 16 minutes in 24 hours.

23 hrs 44 minutes = 356/15 hrs

Now, 356/15 Hrs of this clock = 24 hours of correct clock

89 hours of this clock = 24×15/356×89 = 90 hours of the correct clock, i.e. the correct clock gains one hour over the incorrect clock.

∴The correct time on the fourth day would be 10pm.

Answer 2

Given:

A clock is set at 4am. It loses 16 minutes in 24 hours.

To Find:

What will be the correct time when the clock indicates 9pm on the 4th day?

Solution:

Time from 4am on a day to 9pm on the 4th day = 89 hours

As per the question, 23 hrs 44 minutes of this clock = 24 hours of the correct clock as this clock loses 16 minutes in 24 hours.

23 hrs 44 minutes = 356/15 hrs

Now, 356/15 Hrs of this clock = 24 hours of correct clock

89 hours of this clock = 24×15/356×89 = 90 hours of the correct clock, i.e. the correct clock gains one hour over the incorrect clock.

Hence, the correct time on the fourth day would be 10pm.