1,A group of 5 people is to be chosen from 26 fat and 16 skinny people. How many possible group have exactly 3 fat and 2 skinny people?

2, Using only the digits{0,2,4,6,8,9}how many three digit strings can be formed under the following conditions:

• The 1st digit cannot be 2, 4 or 6
• The 2nd digit has no restriction.
• The 3rd digit cannot match the 1st

3, How many Binary strings of length 7 do notend with 1?