CBSE Guess > Papers > Question Papers > Class X > 2009 > Mathematics > Mathematics

SECTION D

Questions number 26 to 30 carry 6 marks each.

Q. 26 A motorboat whose speed in still water is 5 km/h, takes 1 hour more to go 12 km upstream
than to return downstream to the same spot. Find the speed of the stream.

Sol. Let the speed of the stream = x km/hr
Then the speed of motorboat upstream = (5 – x) km/hr
and the speed of motorboat downstream = (5 + x) km/hr
Distance = 12 km
According to the question,

24x = 25 – x²             x² + 24x – 25 = 0
(x² + 25x – 1x – 25 = 0
x (x + 25) – 1 (x + 25) = 0
(x + 25) (x – 1) = 0
x + 25 = 0 or x – 1 = 0
x = – 25 or x = 1
But speed can not be –ve
Speed of the stream = 1 km/hr.

Mathematics 2009 Question Papers Class X
Delhi		Outside Delhi		Compartment Delhi		Outside Delhi		Foreign
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