Exams


Q:

A box contains 4 different black balls, 3 different red balls and 5 different blue balls. In how many ways can the balls be selected if every selection must have at least 1 black ball and one red ball ?

A) 24 - 1  

B) 2425-1   

C) (24-1)(23-1)25   

D) None 

A) A B) B
C) C D) D
 
Answer & Explanation Answer: C) C

Explanation:

It is explicitly given that all the 4 black balls are different, all the 3 red balls are different and all the 5 blue balls are different. Hence this is a case where all are distinct objects.

 

Initially let's find out the number of ways in which we can select the black balls. Note that at least 1 black ball must be included in each selection.

 

Hence, we can select 1 black ball from 4 black balls
or 2 black balls from 4 black balls.
or 3 black balls from 4 black balls.
or 4 black balls from 4 black balls.

 

Hence, number of ways in which we can select the black balls

 

= 4C1 + 4C2 + 4C3 + 4C4
= 24-1 ........(A)

 

Now let's find out the number of ways in which we can select the red balls. Note that at least 1 red ball must be included in each selection.

 

Hence, we can select 1 red ball from 3 red balls
or 2 red balls from 3 red balls
or 3 red balls from 3 red balls

 

Hence, number of ways in which we can select the red balls
= 3C1 + 3C2 + 3C3
=23-1........(B)

 

Hence, we can select 0 blue ball from 5 blue balls (i.e, do not select any blue ball. In this case, only black and red balls will be there)
or 1 blue ball from 5 blue balls
or 2 blue balls from 5 blue balls
or 3 blue balls from 5 blue balls
or 4 blue balls from 5 blue balls
or 5 blue balls from 5 blue balls.

 

Hence, number of ways in which we can select the blue balls
= 5C0 + 5C1 + 5C2 + … + 5C5
= 25..............(C)

 

From (A), (B) and (C), required number of ways
=  2524-123-1

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Filed Under: Permutations and Combinations
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3 8945
Q:

State game of Madhya Pradesh? 

A) Mallakhamba B) Lagori
C) Kabaddi D) Kho Kho
 
Answer & Explanation Answer: A) Mallakhamba

Explanation:

State_game_of_Madhya_Pradesh1552129369.jpg image

The State game of Madhya Pradesh is Mallakhamba.

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Filed Under: Indian Geography
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11 8940
Q:

There is an empty reservoir whose capacity is 30 litres. There is an inlet pipe which fills at 5 L/min and there is an outlet pipe which empties at 4 L/min. Both the pipes function alternately for 1 minute. Assuming that the inlet pipe is the first one to function, how much time will it take for the reservoir to be filled up to its capacity?

A) 49.5 min B) 50 min
C) 51 min D) 52 min
 
Answer & Explanation Answer: C) 51 min

Explanation:

The work to be done = Capacity of reservoir  = 30 litres.

 1st Minute ---> inlet pipe opened ---> 5 lit filled

 2nd minute ---> inlet pipe closed; outlet pipe opened ---> 4 lit emptied

 

In 2 minutes (5 litres - 4 litres = 1lit) is filled into the reservoir.

It takes 2 minutes to fill 1lit ---> it takes 50 minutes to fill 25 litres into the reservoir.  

 

In the 51st minute inlet pipe is opened and the reservoir is filled.

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24 8937
Q:

The ratio of Karthik’s and Kalyan’s ages is 4: 5. If the difference between the present age of Kalyan and the age of Karthik 5 years hence is 3 years, then what is the total of present ages of Karthik and Kalyan?

A) 56 years B) 62 years
C) 69 years D) 72 years
 
Answer & Explanation Answer: D) 72 years

Explanation:

Let us consider Karthik as K1 and Kalyan as K2.


Given k18+k1 and K2 - (K1 + 5) = 3 

K2 - K1 = 8

K2 = 8 + K1

Now, 

k18+k1= 45

=> K1 = 32 years

Therefore K2 = 40 years.

K1 + K2 = 72 years.

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7 8925
Q:

If the first and third letters in the word NECESSARY were interchanged, also the fourth and the sixth letters, and the seventh and the ninth letters, which of the follwing would be the seventh letter from the left ?

A) E B) S
C) R D) Y
 
Answer & Explanation Answer: D) Y

Explanation:

we interchange the positions of the letters as shown below:

                                  K11483936954.jpg image

The new letter sequence is CENSSEYRA.
Clearly, the seventh letter from the left is Y.

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Filed Under: Alphabet Test
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12 8925
Q:

Each consonant in the word TIRADES is replaced by the previous letter in the English alphabet and each vowel is replaced by the next letter in the English alphabet and the new letters are arranged alphabetically. Which of the following will be the fourth from the right end ?

A) S B) Q
C) J D) U
 
Answer & Explanation Answer: C) J

Explanation:

Given word is TIRADES
Now the consonants T, R, D, S are replaced by S, Q, C, R
And Vowels are I, A, E are replaced by J, B and F
They are arranged alphabetically
New word is BCFJQRS

The fourth letter from the right end is J.

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9 8925
Q:

The headquarters of the coffee board of India is

A) Bangalore B) Mysore
C) Chennai D) Hyderabad
 
Answer & Explanation Answer: A) Bangalore

Explanation:

The Coffee Board of India is an organisation managed by the Ministry of Commerce and Industry of the government of India to promote coffee production in India. The headquarters of the coffee board of India is located in Bangalore, Karnataka.

 

The Coffee Board of India was established by an act of Parliament in 1942.

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7 8918
Q:

There are 44 students in a hostel, due to the administration,  15 new students has joined. The expense of the mess increase by Rs. 33 per day. While the average expenditure per head diminished by Rs. 3, what was the original expenditure of the mess ?

A) Rs. 404 B) Rs. 514
C) Rs. 340 D) Rs. 616
 
Answer & Explanation Answer: D) Rs. 616

Explanation:

Let the average expenditure per head be Rs. p
Now, the expenditure of the mess for old students is Rs. 44p
After joining of 15 more students, the average expenditure per head is decreased by Rs. 3 => p-3
Here, given the expenditure of the mess for (44+15 = 59) students is increased by Rs. 33
Therefore, 59(p-3) = 44p + 33
59p - 177 = 44p + 33
15p = 210
=> p = 14
Thus, the expenditure of the mess for old students is Rs. 44p = 44 x 14 = Rs. 616.

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11 8916