How many 3 letter code combinations are possible using the first 10 letters of English alphbets if: i. no letter can be repeated, ii. letters can be repeated.

How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

How many 4 - letter codes can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

How many 4 -letter code can be formed using the first 10 letters of the English alphabet,if no letter can be repeated?

How many 3 letter words can be formed using the letters of theword INEFFECTIVE?

How many codes containing 3 letters can be formed with the 9 letters of English alphabet if repetition is not allowed?

In how many ways 5 letters can be posted in 4 letter boxes?

How many three letter words can be formed using the letters of the word NARESH? (Repetition of letters is not allowed)

A word of 6 letters is formed from a set of 16 different letters of English alphabet (with replacement). Find out the probability that exactly two letters are repeated.

In how many ways can the letters of the English alphabet be arranged so that there are seven letters between the letters A and B ?

If each vowel of the word 'GRAYHOUND' is changed to the previous letter as in the English alphabetical series and each consonant is changed to the next letter as in the English alphabetical series then in new arrangement how many letters are repeated?