A boat can travel 4.2 km upstream in 14 min. If the repsective ratio of speed of the boat in still water and speed of the stream is 7 : 1. How much time still the boat take to cover 17.6 km downstream ? (in min)
Let the speed of boat in still water be 7x and the speed of stream be x respectively.
In upstream
4.2÷14/60= 7x-x
42×60/14×10 = 6x
x=3 km/h
Now in downstream,
Required time = 17.6/(21+3) = 176/24×10
= 44 hour ⇒ (44/60×60) min = 44 min
In a 140 litre of mixture of milk and water, percentage of water is only 30%. The milkman gave 20 litre of this mixture to a customer. Then he added equal quantities of pure milk and water to the remaning mixture. As a result the respective ratio of milk and water in the mixture became 2:1. What was the quantity of milk added ? (in litres)
A bag contains 5 red balls, 6 yellow balls and 3 green balls. If two balls are picked at random, what is the probability that either btoh are red or both are green in colour
Directions (next five questions) : What will come in place of the question mark (?) in the following number series
7.4 9.2 11.4 14 17 ?
7 24 58 109 ? 262
7 9 18 46 111 ?
