GATE Questions

Q:

The difference between the time taken by two trains to travel a distance of 350 km is 2 hours 20 minutes. If the difference between their speeds is 5 km/hr, what is the speed of faster train ?

A) 36 kmph B) 30 kmph
C) 34 kmph D) 40 kmph
 
Answer & Explanation Answer: B) 30 kmph

Explanation:

Let the speed of the faster train be 'S' kmph

 

Then speed of the slower train will be '(S-5)' kmph

 

Time taken by faster train = 350/S hrs

 

Time taken by slower train = 350/(S-5) hrs

 350s-5 - 350s = 2 hrs 20 min = 213 = 73

 

=> S = 30 km/hr.

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Q:

The mean of 100 observations is 40. It is found that an observation 84 was misread as 48. Then the correct mean is ?

A) 40.36 B) 41.24
C) 41.92 D) 42.05
 
Answer & Explanation Answer: A) 40.36

Explanation:

Given,

mean of 100 observations is 40

=> Total of 100 observations = 40 x 100 = 4000

84 is misread as 48

=> Difference = 84 - 48 = 36

=> Now, new total of 100 observations = 4000 + 36 = 4036

Correct Mean = 4036/100 = 40.36

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Q:

16 women can do a piece of work in 10 days while 15 men can do the same work in 12 days. All men and all women work alternately starting with all men, then find the time taken by them to complete the whole work?

A) 10 5/2 days B) 11 days
C) 11 2/5 days D) 12 1/2 days
 
Answer & Explanation Answer: A) 10 5/2 days

Explanation:

Let efficiency of every man and every woman be 'm' unit/day and 'w' unit/day respectively

15×12×m = 10×16×w

⇒ m/w = 8/9

Total work = 15 × 12 × 9 = 1620 units

In 2 days, total work done = 15 x 9 + 16 x 8 = 263 units

So, in 10 days work done will be = 263 × 5 = 1315 units

Remaining work will be done in = (1620-1315)/(15×8) = 5/2 days

Total days = 10 5/2 days.

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27 7758
Q:

The reactivity of an atom arises from 

A) the existence of unpaired electrons in the valence shell B) the energy differences between the electron shells
C) the sum of the potential energies of all the electron shells D) the average distance of the outermost electron shell from the nucleus
 
Answer & Explanation Answer: A) the existence of unpaired electrons in the valence shell

Explanation:

When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.

 

Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

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Q:

Ronika deposited Rs.7000 which amounted to Rs.9200 after 3 years at simple interest. Had the interest been 2% more. She would get how much ?

A) 9850 B) 9500
C) 9620 D) 9760
 
Answer & Explanation Answer: C) 9620

Explanation:

As the interest rate increases by 2%
=> (7000x3x2)/100 = 420
                                   9200
                                  --------
                                   9620

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Q:

Resistance of human body in dry condition

A) 10 ohm B) 1000 ohm
C) 10000 ohm D) 100000 ohm
 
Answer & Explanation Answer: D) 100000 ohm

Explanation:

Under dry conditions, the resistance offered by the human body may be as high as 100,000(10^5) Ohms.

 

Depending on the person, a rough value for the internal resistance of the human body is 300-1,000 Ohms. The skin's resistance is much lower if it is wet or burnt/blistered.



There are a lot of factors involved and not every person has the same electrical resistance. For instance, men tend to have lower resistance than women.

Within the body, the tissues with the greatest resistance are bone and fat - nerves and muscle have the least resistance.

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Q:

Four person A, B, C and D. The sum of their present age is 176. Four years ago ratio of their age was 11: 9 : 6 : 14, then find who is eldest and youngest among them ?

A) A is eldest & C is youngest B) D is eldest & C is youngest
C) C is eldest & A is youngest D) A is eldest & B is youngest
 
Answer & Explanation Answer: B) D is eldest & C is youngest

Explanation:

Given sum of present ages of A, B, C & D

A + B + C + D = 176

and also given that,

(A-4) : (B-4) : (C-4) : (D-4) = 11 : 9 : 6 : 14

Let the ratio = x

=> A-4 + B-4 + C-4 + D-4 = 11x + 9x + 6x + 14x

=> (A + B + C + D ) - 16 = 40x

=> 176 - 16 = 40x

=> x = 4

=> A = 44 + 4 = 48

=> B = 40

=> C = 28

=> D = 60

Therefore, from the above conclusions

D is eldest with 60 years and C is youngest with 28 years of ages.

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Q:

What is the total no of ways of selecting atleast one item from each of the two sets containing 6 different items each?

A) 2856 B) 3969
C) 480 D) None of these
 
Answer & Explanation Answer: B) 3969

Explanation:

We can select atleast one item from 6 different items = 26-1  

 

Similarly we can select atleast one item from other set of 6 different items in 26-1 ways. 

 

Required number of ways = (26-1)26-1 = 26-12 = 3969

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