Problems on Boats and Streams Part 2

Directions to Solve
Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and
  • Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
  • Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
  • Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
  • Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
  • Give answer(E) if the data in both Statements I and II together are necessary to answer the question.
1. 
A boat takes a total time of three hours to travel downstream from P and Q and upstream back from Q to P. What is the speed of the boat in still water?
I. 
The speed of the river current is 1 km per hour.
 II. 
The distance between P and Q is 4 km.
A.I alone sufficient while II alone not sufficient to answer
B.II alone sufficient while I alone not sufficient to answer
C.Either I or II alone sufficient to answer
D.Both I and II are not sufficient to answer
E.Both I and II are necessary to answer
Answer: Option E
Explanation:
 I. Speed of the current = 1 km/hr.
II. PQ = 4 km.
Let the speed of the boat in still water be x km/hr. Then,
4+4= 3. This gives x.
(x + 1)(x - 1)
 Correct answer is (E).
2. 
What is the speed of the boat in still water?
I. 
It takes 2 hours to cover the distance between A and B downstream.
 II. 
It takes 4 hours to cover the distance between A and B upstream.
A.I alone sufficient while II alone not sufficient to answer
B.II alone sufficient while I alone not sufficient to answer
C.Either I or II alone sufficient to answer
D.Both I and II are not sufficient to answer
E.Both I and II are necessary to answer
Answer: Option D
Explanation:
Let AB = x km.
 I. Speed downstream =xkm/hr
2
II. Speed upstream =xkm/hr.
4
Speed of boat in still water =1(x+x)km/hr.
224
Thus, I and II both even do not give the answer.
 Correct answer is (D).
3. 
What is the speed of the boat in still water?
I. 
The boat covers a distance of 48 kms in 6 hours while running upstream.
 II. 
The boat covers the same distance in 4 hours while running downstream.
A.I alone sufficient while II alone not sufficient to answer
B.II alone sufficient while I alone not sufficient to answer
C.Either I or II alone sufficient to answer
D.Both I and II are not sufficient to answer
E.Both I and II are necessary to answer
Answer: Option E
Explanation:
 I. Speed upstream =48km/hr = 8 km/hr.
6
II. Speed downstream =48km/hr = 12 km/hr.
4
Speed of the boat =1(8 + 12) km/hr = 10 km/hr.
2
Thus, I and II together give the answer.
 Correct answer is (E).

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.
A.I and II only
B.All I, II and III
C.III, and either I or II
D.Any two of the three
E.None of these
Answer: Option D
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 + y4 + 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).

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