A submarine practices attacking a convoy that has 20 cargo ships and 5 escort vessels. In how many different ways could attack
a) A cargo ship and then an escort vessel?
b) A ship or an escort ship?
c) A cargo ship and then another cargo ship?

Question

A submarine practices attacking a convoy that has 20 cargo ships and 5 escort vessels. In how many different ways could attack
a) A cargo ship and then an escort vessel?
b) A ship or an escort ship?
c) A cargo ship and then another cargo ship?

anonymous · Answer

I'm thinking (20 C 1) x (5 C 1) which would be 100 but I'm not sure.. Please help.

misty1212 · Answer

HI!!

misty1212 · Answer

by the counting principle the first one is $20\times 5$

anonymous · Answer

Hi

anonymous · Answer

And so the first is 100

misty1212 · Answer

yes, 20 choices for the first one then 5 for the second, so $20\times 5$

anonymous · Answer

Or means add right so I would add 20 and 5 for part b?

anonymous · Answer

And part c just multiply 20 by 20? Sorry I just want to make sure I get confused with the "and" and "and then"