Q. My husband's watch gains 2 minutes every watch and my watch loses 1 minute for each hour. One day, we were late to marriage because the difference between the time in the two watches was 1 hr and we looked at the slow watch. When did we last set our watches to the same time?

• 1st hr diff 3min 2nd hr 6min 3rd 9min so ap series 3,6,9,12...... diff 60min 60 is 20th term by applng frula of nth trm a+(n-1)d=60 whre d=3,a=3,n=? so they last set dr wtch before 20hr
• 11 years agoHelpfull: Yes(14) No(1)
• Suppose they had set their watches X hours ago.
  Husband's watch gains 2X/60 hour every hour while wife's watch loses X/60 every hour.
  
  Now as one watch gains and other loses the difference will be added
  
  Hence (2X/60) + (X/69)= 1 (hour)
  Thus X= 20 hours.
  Note : If both watches would have gained or if both would have been losing then we would have subtracted the difference.
• 9 years agoHelpfull: Yes(6) No(0)
• ans= 20 hrs
  
• 9 years agoHelpfull: Yes(1) No(0)