GATE Questions

Q:

fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ?

A) 3/91 B) 2/73
C) 1/91 D) 3/73
 
Answer & Explanation Answer: A) 3/91

Explanation:

In a circle of n different persons, the total number of arrangements possible = (n - 1)!
Total number of arrangements = n(S) = (15 – 1)! = 14 !
Taking three persons as a unit, total persons = 13 (in 4 units)
Therefore no. of ways for these 13 persons to around the circular table = (13 - 1)! = 12!
In any given unit, 3 particular person can sit in 3!. Hence total number of ways that any three person can sit =
n(E) = 12! X 3!
Therefore P (E) = probability of three persons sitting together = n(E) / n(S) = 12! X 3 ! / 14!
= 12!x3x2 / 14x13x12! = 6/14x13 = 3/91

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Filed Under: Probability
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Q:

There are two numbers such that the sum of twice the first number and thrice the second number is 100 and sum of thrice the first number and twice the second number is 120. Which is the larger number ?

A) 32 B) 24
C) 26 D) 38
 
Answer & Explanation Answer: A) 32

Explanation:

Let the first number be K and second number be L
Then, 2K + 3L = 100.....(1)
3K + 2L = 120.......(2)
solving (1)&(2), we get
K = 32 and L = 12

Hence the largest number is 32.

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Filed Under: Numbers
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Q:

What color does blue and yellow make?

A) Green B) Black
C) Red D) White
 
Answer & Explanation Answer: A) Green

Explanation:

Mixing of blue and yellow colors make Green Color.

                                 400px-Color_mixture.svg_1521793884.png image

 

RYB (an abbreviation of red–yellow–blue) is a historical set of colors used in subtractive color mixing and is one commonly used set of primary colors. It is primarily used in art and design education, particularly painting.

RYB predates modern scientific color theory, which has determined that cyan, magenta, and yellow are the best set of three colorants to combine, for the widest range of high-chroma colors.

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2 12418
Q:

A Committee of 5 persons is to be formed from a group of 6 gentlemen and 4 ladies. In how many ways can this be done if the committee is to be included atleast one lady?

A) 123 B) 113
C) 246 D) 945
 
Answer & Explanation Answer: C) 246

Explanation:

A Committee of 5 persons is to be formed from 6 gentlemen and 4 ladies by taking. 

 

(i) 1 lady out of 4 and 4 gentlemen out of 6 

(ii) 2 ladies out of 4 and 3 gentlemen out of 6 

(iii) 3 ladies out of 4 and 2 gentlemen out of 6 

(iv) 4 ladies out of 4 and 1 gentlemen out of 6 

 

In case I the number of ways = C14×C46 = 4 x 15 = 60 

In case II the number of ways = C24×C36 = 6 x 20 = 120 

In case III the number of ways = C34×C26 = 4 x 15 = 60

In case IV the number of ways = C44×C16 = 1 x 6 = 6 

 

Hence, the required number of ways = 60 + 120 + 60 + 6 = 246

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Q:

Water flows into a tank which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m x 0.2m) at 20 km/h. In what time will the water level be 12m  ?

A) 200 hrs B) 240 hrs
C) 300 hrs D) 270 hrs
 
Answer & Explanation Answer: C) 300 hrs

Explanation:

Volume of water collected in the tank in 1 hour

⇒ (0.3 × 0.2 × 20km × 1000mts) = 1200 m cubic

If after t hours, the water is at height of 12m,

1200t=200×150×12 

⇒ t = 300 Hours.

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Filed Under: Pipes and Cistern
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25 12379
Q:

In a row of boys, Haran is eleventh from the left and manoj is seventeenth form the right. When they exchange their places than Haran will be thirteenth from the left. Which of the following will be the new position of Manoj from the right ?

A) 11 B) 19
C) 13 D) 17
 
Answer & Explanation Answer: B) 19

Explanation:

exp.

Here total number of boys in the row = 11 + 19 = 13 + 17 = 30

Here after exchanging the places of Haran & Manoj 

=> Manoj replaces Harans place of 11th from left 

But in the question he asked Manoj's place from right = 30 - 11 = 19th place.

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31 12377
Q:

Blotting paper absorbs ink due to

A) Capillary action phenomenon B) Diffusion of ink through the blotting
C) Siphon action D) Viscosity of ink
 
Answer & Explanation Answer: A) Capillary action phenomenon

Explanation:

Blotting paper absorbs ink by the process of capillary action. The capillary action is based on the property of surface tension of liquid.

 

All unsized paper will absorb water. Blotting paper is not sized and made bulkier to provide capillary action for faster absorption of liquid.

 

Blotting paper has also been sold as a cosmetic to aid in the removal of skin oils and makeup.

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Q:

How many meaningful English words can be formed with the letters LGEU using each letter only once in each word ?

A) Zero B) One
C) Two D) Four
 
Answer & Explanation Answer: B) One

Explanation:

'GLUE' is the only meaningful word that can be formed using the letters given.

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Filed Under: Alphabet Test
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