Mathematics Mcqs

A man can row 9 1/3 km/hr in still water and he finds that is thrice as much time to row u p than as to row down the same distance in river. The speed of the current is:________?

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A man can row 9 1/3 km/hr in still water and he finds that is thrice as much time to row u p than as to row down the same distance in river. The speed of the current is:________?

A. 3 1/3 km/hr
B. 3 1/9 km/hr
C. 1 ¼ km/hr
D. 4 2/3 km/hr
Explanation:
Let Speed upstream = x km/hr
Speed downstream = 3x km/hr
Speed in still water = ½ (x+3x) km/hr = 2x km/hr
Speed of current = ½ (3x-x) km/hr = x km/hr
2x = 28/3 or x = 14/3 = 4 2/3 km/hr

A boat travels upstream from B to A and downstream from A to B in 3 hours. If the speed of the boat in still water is 9km/hr and the speed of the current is 3km/hr, the distance A and B is:_______?

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A boat travels upstream from B to A and downstream from A to B in 3 hours. If the speed of the boat in still water is 9km/hr and the speed of the current is 3km/hr, the distance A and B is:_______?

A. 4km
B. 6 km
C. 8 km
D. 12 km
Explanation:
Speed downstream = (9+3) km/hr = 12km/hr
Speed upstream = (9-3) km/hr = 6 km/hr
Distance AB = x km
x/6 + x/12 = 3
=> 2x + x = 36
=> x= 12

A boat takes half time in moving a certain distance downstream than upstream. What is the ratio between the rate in still water and rate of current?

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A boat takes half time in moving a certain distance downstream than upstream. What is the ratio between the rate in still water and rate of current?

A. 1 : 2
B. 3 : 1
C. 2 : 1
D. 1 : 3
Explanation:
Let the speed of the boat in still water be 4 km/hr and speed of the current be u km/hr.
Rate downstream = (u + v) km/hr.
Rate upstream = (u- v)km/hr
Let the distance covered in each case be x km.
Then 2x/(u + v) = x / (u – v)
=> 2 (u – v) = ( u + v)
=> u =3v
=> u/v =3/1

A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will he take to go 5km in stationery water?

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A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will he take to go 5km in stationery water?

A. 40 Minutes
B. 1 Hour
C. 1 hr 15 Min
D. 1 Hr 30 Min
Explanation:
Speed upstream = 2km/hr.
Speed downstream = 6 km/hr
Speed in stationary water = ½ (6 + 2) km/hr = 4 km/hr
Time is taken to cover 5 km in stationary water
= (1/4 x 5) 1 hr 15 min

A can run a kilometer race in 4 1/2 min while B can run same race in 5 min. How many meters start can A give B in a kilometer race, so that the race mat end in a dead heat?

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A can run a kilometer race in 4 1/2 min while B can run same race in 5 min. How many meters start can A give B in a kilometer race, so that the race mat end in a dead heat?

A. 150 m
B. 125 m
C. 130 m
D. 100 m
Explanation:
A can give B (5 min – 4 1/2 min) = 30 sec start.
The distance covered by B in 5 min = 1000 m.
Distance covered in 30 sec = (1000 * 30)/300 = 100 m.
A can give B 100m start.

A can give B 100 meters start and C 200 meters start in a kilometer race. How much start can B give C in a kilometer race?

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A can give B 100 meters start and C 200 meters start in a kilometer race. How much start can B give C in a kilometer race?

A. 111.12 m
B. 888.88 m
C. 777.52 m
D. 756.34 m
Explanation:
A runs 1000 m while B runs 900 m and C runs 800 m.
The number of meters that C runs when B runs 1000 m,
= (1000 * 800)/900 = 8000/9 = 888.88 m.
B can give C = 1000 – 888.88 = 111.12 m.

In a mixture of milk and water, the proportion of milk by weight was 80%. If, in a 180 gm mixture, 36 gms of pure milk is added, what would be the percentage of milk in the mixture formed?

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In a mixture of milk and water, the proportion of milk by weight was 80%. If, in a 180 gm mixture, 36 gms of pure milk is added, what would be the percentage of milk in the mixture formed?

A. 80%
B. 100%
C. 84%
D. 87.5%
E. None of these

Explanation:
Percentage of milk in the mixture formed = [80/100 (180) + 36] / (180 + 36) * 100% = (144 + 36)/216 * 100% = 5/6 * 100% = 83.33%.