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A watch which gains uniformly is 2 minutes low at noon on Monday and is 4 min. 48 sec fast at 2 p.m. on the following Monday. When was it correct?
Answer & Solution
Correct Answer:
Option
B
Time from 12 pm on Monday to 2 pm on the following Monday
= 7 days 2 hours
= 170 hours
∴ The watch gains \[\left( {2 + 4\frac{4}{5}} \right)\] minutes or \[\frac{{34}}{5}\] minutes in 170 hours.
Now, $$\frac{{34}}{5}$$ minutes are gained in 170 hours
∴ 2 minutes are gained in \[\left( {170 \times \frac{5}{{34}} \times 2} \right)\] hours = 50 hours
∴ Watch is correct 2 days 2 hours after 12 pm on Monday i.e., it will be correct at 2 pm on Wednesday.
= 170 hours
∴ The watch gains \[\left( {2 + 4\frac{4}{5}} \right)\] minutes or \[\frac{{34}}{5}\] minutes in 170 hours.
Now, $$\frac{{34}}{5}$$ minutes are gained in 170 hours
∴ 2 minutes are gained in \[\left( {170 \times \frac{5}{{34}} \times 2} \right)\] hours = 50 hours
∴ Watch is correct 2 days 2 hours after 12 pm on Monday i.e., it will be correct at 2 pm on Wednesday.
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