Let n and m be two integers such that n>m >0. If a bit string of length n is randomly selected, what is the probability of selecting a string in which the last m bits are all 1? 0 ㅇ O 2n-m 2n 2" 2m 2n-m 2m None of these. 2m 2"

How many numbers have digits which are all ”1”s and ”2”s, and thedigits add up to 8? A few such numbers are 12212, 112121, and 112121. (HINT: breakthe list into cases and count each one. You can count them by hand, but you will savea lot of time if you apply the right formula.)

How many strings of letters from the set (A, B, C, D, E} are there which have length six, have no repeated letters, and start with the letter 'E' and end with the letter 'A'? O O O 4 × 3 × 2 6x5x4x3 5×4×3×2 None of the other answers listed here is correct. 46 64

only B please

(a) Find the order of a modulo 7 for a = 1, 2, 3, 4, 5, 6.