Question

A mechanical clock is at present showing $7$ hours $40$ minutes $6$ seconds. Assuming that it loses 4 seconds in every hour, what time will it show after exactly $6\frac{1}{2}$ hours?

• A. $14$ hours $9$ minutes $34$ seconds
• B. $14$ hours $9$ minutes $40$ seconds
• C. $14$ hours $10$ minutes $6$ seconds
• D. $14$ hours $10$ minutes $32$ seconds

Answer 1

The correct option is B $14$ hours $9$ minutes $40$ seconds

Time lost in $6\frac{1}{2}$ hours $=6\frac{1}{2}\times 4=26$ seconds.
Correct time after $6\frac{1}{2}$ hours
$=$ $7$ hours $40$ minutes $6$ seconds $+$ $6$ hours $30$ minutes
$=14$ hours $10$ minutes $6$ seconds.
Time shown by the clock
$=14$ hours $10$ minutes $6$ seconds $-26$ seconds
$=14$ hours $9$ minutes $40$ seconds