SATHEE: Permutations And Combinations Question 346

Permutations And Combinations Question 346

Question: The total number of 3-digit numbers, the sum of whose digits is even, is equal to

Options:

A) 450

B) 350

C) 250

D) 325

Show Answer

Answer:

Correct Answer: A

Solution:

[a] Let the number be $ n=pqr. $ As $ p+q+r $ is even, there are following cases: (i) p, q, r all are even $ \to 4.5.5=100 $ ways (ii) p even and q, r are odd $ \to 4.5.5=100 $ ways (iii) p odd, q and r even $ \to 5.5.5=125 $ ways (iv) p odd, q even, r odd $ \to 5.5.5=125 $ Total ways $ =100+100+125+125=450. $

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Permutations And Combinations Question 346

Question: The total number of 3-digit numbers, the sum of whose digits is even, is equal to

Options:

Answer:

Solution:

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