Let Speed of boat in still water = b
Let Speed of still water = w
Then we know that,
Speed of Upstream = U = boat - water
Speed of Downstream = D = boat + water
Given, U + D = 82
b - w + b + w = 82
2b = 82
=> b = 41 kmph
From the given data,
41 - w = 105/3 = 35
w = 6 kmph
Now,
b + w = 126/t
=> 41 + 6 = 126/t
=> t = 126/47 = 2.68 hrs.
So, 135 is wrong.
3rd term = (2nd term) x 2 + 2 = 16 x 2 + 2 = 34.
4th term = (3th term) x 3 + 3 = 34 x 3 + 3 = 105.
5th term = (4th term) x 4 + 4 = 105 x 4 + 4 = 424
6th term = (5th term) x 5 + 5 = 424 x 5 + 5 = 2125
∴ 6th term should 2125 instead of 2124.
So, 80 is wrong.
Downstream speed of boat = Speed of boat in still water + Speed of stream
= 24 + 8 = 32 km/h
? Required time = Distance/Speed downstream
= 128/32 = 4 km/h
Speed of a boat in still water = distance / time = 12/1 = 12 km/h
Speed against the current = 12/3 km/h
Let the speed of the current = x km/h
According to the question,
12 - x = 4
? x = 8 km/h
Speed downstream = (9 + 3) km/hr = 12km/hr
Speed upstream = = (9 - 3) km/hr = 6km/hr
Let the distance AB = d km
Then, d/6 + d/12 = 3
? 2d + d = 36
? d = 12
? Distance AB = 12 km
If the first Saturday of June is in lst. Then, next Saturday will be on 8th, 15th , 22nd and 29th. So , last Saturday will be on 29th.
Speed downstream = 48/20 = 2.4 km/h
Speed upstream = 48/24 = 2 km/h
? Speed of boat in still water = (Speed downstream + Speed upstream)/2
= (2.4 + 2)/2 = 4.4/2 = 2.2 km/h
Required probability = P(A) x P(B)
= (7/8) x (9/10)
= 63/80
Speed upstream = Distance/Time = 60/10 = 6 km/h
Speed upstream = Distance/Time = 36/10 = 3.6 km/h
? Velocity of the current = (speed downstream - Speed upstream)/2
= (6 - 3.2)/2 = 1.2 km/h
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