Question

A code word of 4 letters consists of two distinct consonants from the English alphabets followed by two digits from 1 to 9, with repetition allowed in digits. If the number of code words so formed ending with an even digit is $432\times k$, then $k$ is equal to

• A. 7
• B. 35
• C. 49
• D. 5

Answer 1

The correct option is B

35

Number of code words ending with even digit

$=21\times 20\times 9\times 4$ [Because there are 21 consonants and the last place can be occupied by any one of $2,4,6,8$]

$\therefore 432\times k=21\times 20\times 9\times 4$

$\Rightarrow k=35$