GATE Questions

Q:

Derivative of sinx by first principle?

A) -sinx B) -cosx
C) cosx D) sinx
 
Answer & Explanation Answer: C) cosx

Explanation:

Screenshot_(1)1519127168.png image

 

Thus, the derivative of sinx by first principle is cosx.

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4 5980
Q:

Raghu can do a job in 12 days alone and Sam can do the same job in 15 days alone. A third person Aru whose efficiency is two-third of efficiency of both Ram and Shyam together, can do the same job in how many days alone?

A) 10 B) 12
C) 13 D) 15
 
Answer & Explanation Answer: A) 10

Explanation:

One day work of Raghu and Sam together = 1/12 + 1/15 = 9/60 = 3/20

Aru efficiency = 2/3 of (Raghu + Sam)

Number of days required for Aru to do thw work alone = 3/2 x 20/3 = 10 days. 

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Filed Under: Time and Work
Exam Prep: AIEEE , Bank Exams , CAT , GATE
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9 5978
Q:

How long will it take for two pipes A and B to fill an empty cistern if they worked alternately for an hour each ?

A. Working alone, Pipe A can fill the cistern in 40 hours
B. Pipe B is one third as efficient as Pipe A

A) Only A is sufficient B) Only B is sufficient
C) Both (A) and (B) are sufficient D) None
 
Answer & Explanation Answer: C) Both (A) and (B) are sufficient

Explanation:

From statement A, we know that Pipe A can fill the tank in 40 hours. However, this information is not sufficient as we do not have the data for Pipe B. Hence, statement A alone cannot answer the given question.

From statement B, we know that Pipe B is one third as efficient as pipe A. However, we do not know the rate at which Pipe A fills the tank. Hence, we will not be able to find the rate at which Pipe B fills the cistern. Therefore, statement B alone is not sufficient to answer the question.

Now, if we combine the two statements, we know that Pipe A take 40 hours to fill the cistern.
Pipe B takes 120 hours to fill the cistern.

If they worked alternately, then either Pipe A could have started the cycle or Pipe B could have started the cycle.

If Pipe A started the sequence of filling alternately, then at the end of two hours, the two pipes together would have filled 1/40 + 1/120 = 1/30  th of the tank in an hour. Or the cistern will fill in 30 hours.

If Pipe B started the sequence, then at the end of 2 hours, the two pipes together would have filled 1/120 + 1/40 = 1/30 th of the tank in an hour. Or the cistern will fill in 30 hours.

As the answer obtained irrespective of which pipe started the sequence is the same, the correct answer is (3) - i.e., both the statement are sufficient to answer the question.

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Filed Under: Statement and Conclusions
Exam Prep: AIEEE , Bank Exams , CAT , GATE
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4 5977
Q:

Salaries of Karthik, Arun and Akhil were in the ratio 4 : 5 : 6 respectively. If their salaries were increased by 50 per cent, 60 per cent and 50 per cent respectively, what will be the new ratio of the salaries of Akhil, Arun and Karthik ?

A) 6 : 8 : 9 B) 8 : 6 : 9
C) 9 : 8 : 6 D) 6 : 5 : 4
 
Answer & Explanation Answer: C) 9 : 8 : 6

Explanation:

Given the salaries are in the ratio of 4 : 5 : 6

 

Now the salaries are increased by 50%, 60% and 50% respectively

 

The New ratio of salaries will be

 

4 x (150/100) : 5 x (160/100) : 6 x (150/100)

 

= 6 : 8 : 9

 

The new ratio of salaries of Akhil, Arun and Karthik is 9 : 8 : 6

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Filed Under: Ratios and Proportions
Exam Prep: GRE , GATE , CAT , Bank Exams
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12 5971
Q:

'K' cycled from A to B at 10 kmph and returned at the rate of 9 kmph. 'L' cycled both ways at 12 kmph. In the whole journey 'L' took 10 minutes less than 'K'. Find the distance between A and B ?

A) 32.1 km B) 15.23 km
C) 3.75 km D) 32.1 m
 
Answer & Explanation Answer: C) 3.75 km

Explanation:

Let 'd' be the distance between A and B
K -time = d/10 + d/9 = 19d/90 hours
L -time = 2d/12 = d/6 hours
We know that, 10 min = 1/6 hours
Thus, time difference between K and L is given as 10 minutes.
=> 19d/90 - d/6 = 1/6
=> (19d-15d)/90 = 1/6
=> 4d/90 = 1/6
Thus,
d= 15/4 km = 3.75 km.

hence the distance between A and B is 3.75 km.

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Filed Under: Time and Distance
Exam Prep: AIEEE , Bank Exams , CAT , GATE , GRE
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3 5970
Q:

A Cricket team of 23 people all shake hands with each other exactly once. How many hand shakes occur ?

A) 142 B) 175
C) 212 D) 253
 
Answer & Explanation Answer: D) 253

Explanation:

The first person shakes hands with 22 different people, the second person also shakes hands with 22 different people, but one of those handshakes was counted in the 22 for the first person, so the second person actually shakes hands with 21 new people. The third person, 20 people, and so on...
So,
22 + 21 + 20 + 19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1
= n(n+1)/2 = 22 x 23 /2 = 11 x 23 = 253.

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Filed Under: Permutations and Combinations
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4 5968
Q:

Which of the following statements is correct?

 

A) I am very happy to start this Program B) I am too happy to start this Program
C) Both A & B D) None
 
Answer & Explanation Answer: A) I am very happy to start this Program

Explanation:

Here I am very happy to start this Program is correct statement.

"Too" is not used with pleasant adjectives. It means 'more than required' and is usually used with unpleasant adjectives.

So, 'too healthy', 'too happy', 'too glad' etc are wrong.

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13 5956
Q:

A passenger train is moving at a speed of 120 km/hr. If the length of the train is 101 meters, how long will it take to cross a railway platform 154 meters long ?

A) 6.24 sec B) 6.58 sec
C) 7.325 sec D) 7.65 sec
 
Answer & Explanation Answer: D) 7.65 sec

Explanation:

Here total distance = 154 + 101 = 255 mts
Given speed = 120 kmph = 120x5/18 m/sec
Hence, Time = d/s = 255x18/120x5 = 7.65 sec

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Filed Under: Problems on Trains
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