Probability of coins

Question

There are 6 pennies, 4 nickels and 3 dimes in a wallet. Three coins are drawn at random without replacement.

What is the probability 3 are pennies?

What is the probability at least one is a penny?

Answer 1

a) 3 pennies out of three draws is just the P(p) without replacement: (6/13)(5/12)(4/11)

b) at least one p is 1 - P(no pennies) : 1 - (7/13)(6/12)(5/11)