At 7 a.m., a watch that gains 5 seconds every 3 minutes was set. When the watch reads quarter past 4 o'clock in the afternoon of the same day, the real time is:
A. 59 7/12min. past 3
B. 4 p.m.
C. 58 7/11min. past 3
D. 3/11min. past 4
Answer:B
At 7 a.m., a watch that gains 5 seconds every 3 minutes was set. When the watch reads quarter past 4 o'clock in the afternoon of the same day, the real time is:
A. 59 7/12min. past 3 B. 4 p.m. C. 58 7/11min. past 3 D. 3/11min. past 4
Explanation: Time from 7 a.m. to 2 3/11 min. past 4 4.15 p.m. to 4.15 p.m. = 9 hours 15 minutes = 37/4 hoursThis clock's 3 minutes and 5 seconds equals the right clock's 3 minutes and 5 seconds.=1/20 hr of the proper clock = 37/720 hr of this clock=1/20 x 720/37 x 37/4 hour of this clock= 1/20 x 720/37 x 37/4 hr of the proper clock= 9 hours of correct time, 9 hours after 7 a.m. is the correct time. 4 p.m., to be exact.