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**panelopy123** >>2)the english alphabet contains 21 consonants and five vowels.how many strings of six lowercase letters of the english alphabet contain>

a)exactly one vowel? ans:122523030>

b)exactly two vowels? ans:72930375>

c)atleast one vowel? ans:223149655>

d)atleast two vowels?>

)how many bit strings contain exactly 8 0s and 10 1s if every 0 must be immediately followed by a 1? ans:45>

4)how many bit strings of length 10 contain atleast three 1s and atleast three 0s?ans:9125)

there are 6 runners in the 100-yard dash.how many ways are there for three medals to be awarded if ties are possible?(the runner or runners who finish with the fastest time receive gold medals,the runner or runners who finish with exactly one runner ahead receive silver medals, and the runner or runners who finish with exactly two runners ahead receive bronze medals).ans:873>

6)how many 4-permutations of +ve integers not exceeding 100 contain three consecutive integers k,k+1,k+2 in the correct order

a)where these consecutive integers can perhaps be separarted byother integers in the permutation?ans:37927>

b)where they are in consecutive positions in the permutation?ans:18915>

i don't know how to solve and have exams