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 7km/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 ?
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 = 15km/hour ∴ Speed of Boat must be 15km/hour
(43/10) + (4.2/1.2) - (2.7/3) = (?/4) + (2.7/6.0)
(15/8) x [6924 – 2124] + 910 = ? + 190
(-251 × 21 × -12) ÷ ? = 158.13
5/2 of 5/6 of 12/5 of 54 % of 5250 = ?
(1/8) × (256 × 2)/(8 × 4) + ?3 = 1730
525 ÷ 21 x 28 – 853 + 264 = ?
24 × √? + 4008 ÷ 24 = 40% of 200 + 327
[(82× 162)/12] - 28 = ?
13/3 – (23/6) = ? – (22/9)