67. A watch which gains uniformly, is 5 min. slow at 8 o’clock in the morning on Sunday and it is 5 min. 48 sec. fast at 8 p.m. on following Sunday. When was it correct?
A.Monday B.Tuesday
C.Wednesday D.Thursday
Answer:
Time from 8 a.m. on Sunday to 8 p.m. on following Sunday = 7 days 12 hours = 180 hours.
∴ The watch gains [5+5 4/5] min. or 54/5 min. in 180 hrs.
Now 54/5 min. are gained in 180 hrs.
∴ 5 min. are gained in [180 * 5/54 * 5] hrs. = 83 hrs 20 min. = 3 days 11 hrs 20 min.
∴ It will be correct at 20 min. past 7 p.m. on Wednesday.
