A person started two watches, he observed that after one hour, one watch gains 1 min/hr and the second watch loses 2 min/hr. After how much time will the two watches have a difference of one hour
2006-07-31 15:09:18 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
20 hours. After one hour, the watches are 3 minutes apart. After 2 hours, they are 6 minutes apart, etc, etc. So if they gain a difference of 3 minutes every hour, and there are 60 minutes in an hour, divide 60 by 3 to get 20 hours.
2006-07-31 15:16:38 · answer #1 · answered by nighthawk_842003 6 · 2⤊ 0⤋
In 20 hours, the two watches will be one hour apart. In that time, the one watch will have gained 20 minutes while the second will have lost 40 minuts.
2006-07-31 22:13:20 · answer #2 · answered by Steve R 3 · 0⤊ 0⤋
2 minutes -1 minute = 1 minute (the difference after one hour.)
For there to be 60 minutes difference, it will take 60 hours, which would be two and one-half days.
2006-07-31 22:16:57 · answer #3 · answered by John (Thurb) McVey 4 · 0⤊ 0⤋
*AFTER ONE HOUR
Ist watch = +1 min
2nd watch = -2 mins
____________________________
*THE DIFFERENCE AFTER ONE HOUR
1-(-2) = 3 mins/hr -----> the difference after 1 hour
____________________________
1 hr = 60 mins
*IN THE EQUATION:
3 mins = the difference after 1 hour
1 hr = after one hour
60 mins = the difference of 1 hour (1 hour = 60 mins)
a = the time needed until the two watches have a difference of one hour
3 mins/1 hr = 60 mins/a hr ------> (cross multiply) and you''ll get
(3 mins) (a hr) = (60 mins) (1 hr)
(3 mins) (a hr) = **60 mins
**(60 mins = 1 hr, so 1hr x 1hr = 1hr or 60 mins)
a hr = 60 mins/3 mins
a = 20 hrs
The answer is 20 hours!!! :P
2006-08-01 09:10:38 · answer #4 · answered by Anonymous · 0⤊ 0⤋
30 hours
2006-08-01 09:34:40 · answer #5 · answered by Anonymous · 0⤊ 0⤋
From what you told me after every hour there is three minutes difference between the two watches.
After twenty hours at three minutes an hour there will be sixty minutes.
Answer= twenty hours
2006-07-31 22:17:21 · answer #6 · answered by eric l 6 · 0⤊ 0⤋
30 hours
2006-07-31 22:14:40 · answer #7 · answered by praveenvis 1 · 0⤊ 0⤋
20 hours forgot to explain....other answers did that....3 minutes separation an hour...hence X * 3 = 60 or 60/3=X or x=20
2006-07-31 22:12:56 · answer #8 · answered by sfs_onfridays 2 · 0⤊ 0⤋
The answer is 20 hours but how do you know that the control watch is accurate?
2006-07-31 22:21:56 · answer #9 · answered by Neil S 4 · 0⤊ 0⤋