Answer & Explanation
Answer: Option D
Explanation:
Let the speed of the train be x m/sec.
III gives that the men are moving in the same direction.
I gives, time taken to pass a man = $$\frac{l}{(x - 3 * \frac{5}{18})}$$
= ($$\frac{6l}{6x - 5}$$)sec.
$$\therefore$$ $$\frac{6l}{6x - 5}$$ = 9
=> 54x - 6l = 45
=> 18x - 2l = 15 ...(i)
II gives, time taken to pass another man = $$\frac{l}{(x - 6 * \frac{5}{18})}$$sec
= $$\frac{3l}{(3x - 5)}$$sec.
$$\therefore$$ $$\frac{3l}{(3x - 5)}$$ = 10
=> 30x - 3l = 50 . . .(i)
On solving (i) and (ii), we get : x = $$\frac{55}{6}$$m/sec.
Thus, all I, II, III are needed to get the answer.
Question 51 . What is the speed of the train?1. The train crosses a signal pole in 13 seconds2. The train crosses a platform of length 250 meters in 27 seconds3. The train crosses another train running in the same direction in 32 seconds
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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 train? I. The train crosses a signal pole in 18 seconds. II. The train crosses a platform of equal length in 36 seconds. III. Length of the train is 330 metres. | |||||||||||||||||||||||||||||||||||
Answer: Option D Explanation: Let the speed of the train be x metres/sec. Time taken to cross a signal pole :
Time taken to cross a platform
Length of train = 330 m. I and III give,
II and III give,
View Answer | Workspace | Report | Discuss in Forum |
2. | What is the speed of the train? I. The train crosses a tree in 13 seconds. II. The train crosses a platform of length 250 metres in 27 seconds. III. The train crosses another train running in the same direction in 32 seconds. | |||||||||||||||||||||||||||
Answer: Option A Explanation: Let the speed of the train be x metres/sec.
Time taken to cross a platform
Thus I and II give the speed of the train. View Answer | Workspace | Report | Discuss in Forum |
3. | What is the speed of the train? I. The train crosses 300 metres long platform in 21 seconds. II. The train crosses another stationary train of equal length in 19x(1/2) seconds. III. The train crosses a signal pole in 9x(3/4) seconds. | |||||||||||||||
Answer: Option B Explanation: Let the speed of the train be x m/sec. Time taken to cross a signal pole
Time taken to cross a platform
I gives, 21 = (l + 300)/x; II gives, 39/2 = 2l/x; III gives, 39/4 = l/x. Thus, (I and II) or (I and III ) give x. Correct answer is (B) View Answer | Workspace | Report | Discuss in Forum |