Q29 of 31 Page 7

Using the digits 1, 2, 3, 4, 5, 6,7. how many 3 digits even numbers can be made, no digit being repeated?

We need to find 3 digits even number using 1,2,3,4,5,6,7


So, units place can have 2,4,6


Number of even numbers if 2 is at unit place


As 2 is fixed next two places can be filled in 5P2 ways




= 20


Similarly, if 4 will be at unit place, 3-digits number will be 20.


Also, if 6 will be at unit place, 3-digits number will be 20.


So, total 3-digits number will be 20+20+20 = 60


More from this chapter

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27

Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements,
i) do the words start with p

ii) do all the vowels always occur together


iii) do all the vowels never occur together


iv) do the words begin with I and end in P?

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If all letters of word ‘MOTHER’ are written in all possible orders and the word so formed are arranged in a dictionary order, then find the rank of word ‘MOTHER’?

 30

From a class of 25 students, 10 are to be chosen for an excursion party. There are 3 students who decide that either all of them will join or none of them will join. In how many ways can the excursion party be chosen?

 31

What is the number of ways of choosing 4 cards from a deck of 52 cards? In how many of these,

(a) 3 are red and 1 is black.


(b) All 4 cards are from different suits.


(c) are face cards.


(d) All 4 cards are of the same suit.