a motorist leaves the post office to go to the airport to collect mail the plain arrives early and the mail is send on a horse cart. after half an hour the motorist meet the horse cart, collects the mail and returns to the post office, thus saving 20 min. how many mins early did the plane arrived?
i)20 min
ii)25 min
iii)30 min
iv)40 min

• 4o minutes, because of language problem it is necessary to understand that hourse cart speed will be less than a motorist, so here half an hour is taken by hourse cart to reach where the motorist meets him, so now the time early plane arrives will be: 30min + 20/2 = 40 minutes..
• 10 years agoHelpfull: Yes(1) No(0)
• Assuming horse-cart travelled half an hour and met the motorist.
  
  Suppose, horse-cart met motorist at time t
  
  Then, plane arrived 30 minutes before t (∵ horse-cart travelled 30 minutes after the plane arrived)
  
  Let distance travelled by horse cart in its 30 minute journey be x. Then, motorist saved 20 minutes by avoiding the distance of (x+x)=2x. In other-words, motorist needs only 10 minute to cover the distance x.
  
  Therefore, if horse-cart was not there, motorist would have reached the airport 10 min after t
  => If horse-cart was not there, motorist would have reached the airport 40 min after plane arrived.
  
  If plane was arriving at the right time, motorist would also have reached at the same time.
  
  Therefore, the plane arrived 40 minutes early.
• 6 years agoHelpfull: Yes(1) No(0)
• 20 min early..as 10 min taken by cart to reach the place where motorist meets the cart after 30 min from the post office.on a return trip motorist saves 10 min and 10 min used by cart to reach the meeting place so plane woud have arrived 20 min early
• 11 years agoHelpfull: Yes(0) No(2)