Question
A motor boat goes downstream from point A to B ,which is
36 km away from point A, and then returns to A. If actual speed of the boat in still water is 7 km/hour , and the total upstream and downstream journey takes 21 hours .What must be the actual speed of boat for the journey from A to B to take exactly 108 minutes?Solution
Speed of boat in still water is 7km/hour Let the Speed of Stream be x Km/hour 36/(7+x) + 36/(7-x) = 21 24 = 49- x2 x = 5 km/hour Now, the speed of Boat for the journey from A to B to take time 108 minutes is Speed of boat = y km/hour , Speed of stream =5km/hour , Time = 108 minutes (y+5) = (36×60)/108 = 20km/hour y+5 = 20 y = 15 km/hour ∴ Speed of Boat must be 15 km/hour.
The cost of 2 pencils and 3 pens is RS. 55 and the cost of 7 pencils and 2 pens is RS. 65. What is the total price (in RS) of 2 pens and one pencil?
The cost of 2 pencils, 4 pens, and 8 erasers is Rs. 24 and the cost of 8 pens, 10 pencils, and 4 erasers is Rs. 36. How much will 3 pencils, 3 pens, and...
A worker is paid Rs. 600 for 50 hours per week. Up to 60 hours, he is paid at the normal rate and for over time, twice the normal. How many hours does h...
Two pipes A and B fill a square tank in 28 and 36 hours respectively while a third pipe C can empty it in 63 hours If all three pipes are opened togethe...
If the cost of 4 pens and 6 notebooks is ₹ 600, then find the cost of 6 pens and 9 notebooks.
A worker is paid Rs. 600 for 50 hours per week. Up to 60 hours, he is paid at the normal rate and for over time, twice the normal. How many hours does h...
Unit digit of a three digit number is 2 more than its tenth digit. If 311 is subtracted from number, then, the number obtained is 13. Find sum of digits...
A is twice as good a workman as B and together they finish a piece of work in 14 days. The number of days taken by A alone to finish the work isÂ
A cistern is normally filled in 18 hours, but it takes 12 hours longer to fill because of a leak at its bottom. If the cistern is full, how long will it...
A certain no. of candidates who appeared for a Bank exam and 5/12 of the candidates were rejected in pre exam, 60% of the rest candidates were rejected ...
Relevant for Exams:
