Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - Data Sufficiency 2 (Q.No. 1)
Directions to Solve
Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.
1.
What is the speed of the boat in still water? | |
I. | The speed downstream is 12 kmph. |
II. | The speed upstream is 4 kmph. |
III. | In a to and fro journey between two points, the average speed of the boat was 6 kmph. |
Answer: Option
Explanation:
| From I and II, speed of boat in still water = | 1 | (12 + 4) km/hr = 8 km/hr. |
| 2 |
From II and III, we get:
| Using average speed = | 2xy | , we get: | 2 x 4 x y | = 6 |
| x + y | 4 + y |
8y = 24 + 6y
y = 12.
 Required speed = |
1 | (12 + 4) km/hr = 8 km/hr. |
| 2 |
Similarly, I and III also give the answer.
Correct answer is (D).
Discussion:
11 comments Page 1 of 2.
Kapadiya sagar said:
5 years ago
Options 1 and 3 become same.
a+b = 6kmph.
So with one equation two unknown is not solvable.
So, the Correct option is [A].
a+b = 6kmph.
So with one equation two unknown is not solvable.
So, the Correct option is [A].
ABHILASHA said:
7 years ago
3rd statement itself is enough as [(u+v)+(u-v)]/2=6.
Which gives u = 6; where u is the speed of the boat in still water and v is the speed of the stream.
Which gives u = 6; where u is the speed of the boat in still water and v is the speed of the stream.
Priya said:
7 years ago
123+45=168,
168*0=0,
Therefore the answer is 0.
But unfortunately, the answer is not 0.
Because any answer cannot be 0.
So, we increment the answer by 1 to avoid any problems.
Therefore the answer is 1.
168*0=0,
Therefore the answer is 0.
But unfortunately, the answer is not 0.
Because any answer cannot be 0.
So, we increment the answer by 1 to avoid any problems.
Therefore the answer is 1.
HarshaVardan said:
8 years ago
My Analysis.
Upstream is 4kmps and downstream is 12kmps.
Boat speed still in water =(down stream+upstream)/2 = (1/2) * (12+4) = 8kmps.
Boat speed against the water =(down stream-upstream)/2 = (1/2) * (12-4) = 4kmps.
So, Statments 1&2 are efficient to get this answer.
Answer is Option "A".
Upstream is 4kmps and downstream is 12kmps.
Boat speed still in water =(down stream+upstream)/2 = (1/2) * (12+4) = 8kmps.
Boat speed against the water =(down stream-upstream)/2 = (1/2) * (12-4) = 4kmps.
So, Statments 1&2 are efficient to get this answer.
Answer is Option "A".
Shashi said:
8 years ago
How is statement 3 related to question?
There is no need of 3rd statement or no relation b/w 3rd to another statement.
There is no need of 3rd statement or no relation b/w 3rd to another statement.
Swarnashree said:
9 years ago
Why x is taken as speed of the boat upstream?
Rahul said:
10 years ago
x is the speed of the boat upstream, and y is the speed of the boat downstream.
AASHIT said:
1 decade ago
Why has 4 been substituted for 'x' when 4=x+y?
Aman said:
1 decade ago
Can anybody tell me how we get the value 4 in that average speed formula you have putted.
Amit said:
1 decade ago
Avg. speed = Total distance / Total time = 2L / t1 + t2.
Time = distance / speed so, t1 = L / x and t2 = L / y.
t1 + t2 = L(x+y) / xy.
Total time = L(x+y) / xy.
Total distance = 2L.
Avg. speed = 2xy/x+y.
Time = distance / speed so, t1 = L / x and t2 = L / y.
t1 + t2 = L(x+y) / xy.
Total time = L(x+y) / xy.
Total distance = 2L.
Avg. speed = 2xy/x+y.
(2)
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