18. 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?
A. 2 p.m. on Tuesday B. 2 p.m. on Wednesday
C. 3 p.m. on Thursday D. 1 p.m. on Friday
Answer:
Time from 12 p.m. on Monday to 2 p.m. on the following Monday = 7 days 2 hours.
=170 hours.
The watch gains = (2 + 4 x4/5)min
= 34 / 5 min.in 170 hrs.
Now,34/5 min are gained in 170 hrs.
2 min are gained in(170x 5/34 x2)hrs.
Watch is correct 2 days 2 hrs. after 12 p.m. on Monday i.e., it will be correct at 2 p.m.on Wednesday.
