Question
A boat can travel 12 km more in downstream than that in
upstream, in 3 hours while the difference between the time taken by the same boat to travel 180 km and 120 km, in still water, is 4 hours. Find the approximate time taken by the boat to travel 267 km in downstream and 183 km in upstream.Solution
Let the speed of boat in still water and speed of stream be 'x' km/hr and 'y' km/hr, respectively. According to question; (180/x) - (120/x) = 4 Or, (60/x) = 4 So, x = 15 Now, 3 x (15 + y) = 3 x (15 - y) + 12 Or, 45 + 3y = 45 - 3y + 12 Or, 6y = 12 So, y = 2 So, downstream speed of the boat = (15 + 2) = 17 km/hr And, upstream speed of the boat = (15 - 2) = 13 km/hr Required time taken = (267/17) + (183/13) ~ (16 + 14) ~ 30 hours
On a clean glass plate, a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because:
What is the simplest hydrocarbon?
Flemings right hand rule is used to find the direction of the –
Which of the following does not give effervescence with sodium carbonate?
Which of the following is the most abundant element on earth?
The atomic bomb is based on which principle?
Which element gives hardness to stainless steel?
Which of the following is the most electronegative element in the periodic table?
In the synthesis of aspirin (acetylsalicylic acid) from salicylic acid, which reagent is used?
Magnesium oxide (MgO) + Water (H2O) = ?
