1)how many numbers between 2500-6500

using 1,2,3,4,5,6,7 without any repitition

i answered

5P1 3P1 7P1 7P1=735

2)Jack needs to answer 5 out of 8 questions find the number of combinations of answers if he can answer any 5 questions

i answered

8C5=56

b)if he has to answer 3 out of 4 in paper A and 2 out of 4 in paper B

i answered

4C3 4C2= 24

3)6 members must be chosen from 7 boys and 5 girls

a) if there are no restrictions

i answered

12C6=924

b)there are not more than 2 girls

5C2 7C4= 350

c) there are 4 girls

5C4 7C2=105

could anyone verify if i am right or wrong.....and please tell me where i went wrong....please