27. a)In how many ways can a committee of 3 be chosen from an organization with 12 members?

My answer: Number of Ways (12 3) = 220 ways

b)In how many ways can a president, vice-president, and treasurer be chosen from this same organization?

My answer: C (12, 3) = 12! divided by 4! 3! = 3,326,400 different ways

28.a) How many 4-digit numbers can be formed from the set A = {0,1,2,3,4,5,6} if there is no repetition? (Note: 0123 is not a 4-digit # because it equals 123)

My answer: Number of digits = (7 4) x 4! -1 ( minus one to get rid of the 0123 choice)

= 839 4 digit numbers can be formed

b)How many of the numbers in part a) are odd

My answer: number of odd digits = 8 x 8 x 7 x 5 = 2240 odd digits This doesn't make sense because there can't be more odd digits than there are total choices in a)

b)How many of the numbers in part a) contain a 3?

** any clues?

Ahh, this is due tomorrow so please let me know if they are right! Thank you