1.

aumbers 23 to 30 carry 4 marks each.motor boat whose speed is 18 km/hr in still water takes 1 hr more to go 24 kmvupstream than to retdownstream to the same spot. Find the speed of the stream.OR

Answer»

speed=distance/time so, time=distance/speed For upstream : t+1=24/18-s (Where s is speed of stream) For downstream : t=24/18+s => (24/18-s)-1=(24/18+s) =>(24/18-s)-(24/18+s)=1 =>s^2+48s-324=0 =>(s+54)(s-6)=0 so, speed of stream=6km/hr.



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