Question
Speed of a boat in still water is 4 times more than the
speed of stream. If boat covers 108 km in downstream in 9 hours, then find the time taken by the boat to cover 80 km in upstream.Solution
Let the speed of stream be ‘x’ km/hr. So, speed of boat in still water = 5 × x = 5x km/hr Downstream speed of boat = 5x + x = 6x km/hr According to question; 6x = 108/9 = 12 Or, x = 2 Upstream speed of the boat = 5x – x = 4x = 4 × 2 = 8 km/hr Required time taken = 80/8 = 10 hours
If x ,y,z are three integers such that x +y = 8,y +z =13 and z +x =17,then the value of x2 /yz  is:
Simplify:
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