Question

Ramu purchased a second hand Swiss watch which is very costly. In this watch the minute-hand and hour hand coincide after every $65\frac{3}{11}$ minutes. How much time does the watch lose or gain per day?

• A. $4$ min
• B. $5$ min
• C. $4$ min, $20$ sec
• D. None of these

Answer 1

The correct option is A $4$ min

You must know that a correct watch coincide just after $65\frac{5}{11}$ min. Therefore in every $65\frac{5}{11}$ hours the watch gains $\frac{2}{11}$ . Hence, in 24 hours it will gain
$\frac{2}{11}\times \frac{11}{720}\times 24\times 60=4$ min.