WB JEE 2022 | Permutations and Combinations Question 15 | Mathematics

WB JEE 2022

MCQ (Single Correct Answer)

-0.25

There are n white and n black balls marked 1, 2, 3, ...... n. The number of ways in which we can arrange these balls in a row so that neighbouring balls are of different colours is

(n!)²

(2n)!

2(n!)²

$${{(2n)!} \over {{{(n!)}^2}}}$$

WB JEE 2021

MCQ (Single Correct Answer)

-0.25

Five letter words, having distinct letters, are to be constructed using the letters of the word 'EQUATION' so that each word contains exactly three vowels and two consonants. How many of them have all the vowels together?

3600

1800

1080

900

WB JEE 2021

MCQ (Single Correct Answer)

-0.25

What is the number of ways in which an examiner can assign 10 marks to 4 questions, giving not less than 2 marks to any question?

WB JEE 2020

MCQ (Single Correct Answer)

-0.25

In a 12 storied building, 3 persons enter a lift cabin. It is known that they will leave the lift at different floors. In how many ways can they do so if the lift does not stop at the second floor?

120

240

720

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