Bunuel
A ship develops a leak 12 km from the shore. Despite the leak, the ship is able to move towards the shore at a speed of 8 km/hr. However, the ship can stay afloat only for 20 minutes. If a rescue vessel were to leave from the shore towards the ship and it takes 4 minutes to evacuate the crew and passengers of the ship, what should be the minimum speed of the rescue vessel in order to be able to successfully rescue the people aboard the ship?
A. 53 km/hr
B. 44 km/hr
C. 37 km/hr
D. 28 km/hr
E. 26 km/hr
good question took me a while , if anyone has someother solution then please share...
speed of ship 8 km /hr
since we have only 20 mins available & it takes 4 mins to rescue people + staff
so lets assume that ship will continue to sail towards shore for 16 mins
distance covered in 16 mins would be
d= 8 * 16/60 = 2.13 kms
distance left from shore 12-2.13 = 9.86 kms
let 9.86 km be the distance that rescue boat has to cover to reach out to ship
so time it would take has to be close to 16 mins..
lets plug in values from answer choices
option B 44 km/hr it time to cover 9.86 kms ; 9.86*60/ 44 = ~ 13.44 mins which is too fast
option C 37 km/hr , time to cover 9.86 kms ; 9.86*60/37 = 16 mins .. which is exact
IMO C is correct...
GMATinsight sir the method i did to solve this question is too calculation intensive, please advise on a short cut method.. I think this question can also be solved using relative speed as well, but i was not able to equate the two eqns for both boats.. please check...