Maths question...need assistance please.

stamina9008

Stuck on these questions, and with the answers and a brief explanation i think it will help me greatly.
Please help....

Three cards are picked from a pack of cards. Each card is picked and then PUT BACK into the pack. What is the probability that the cards consist of:

A. Three red cards - I assume this is 1/2 x 1/2 x 1.2 = 1/8?

But...these..

B. No picture cards - Picture cards in a deck = 12/52 but im stuck on what to do next..

C. Exactly one ace

D. AT LEAST one spade

I really dont understand probability..

InsideInsurance

B = 10/13 * 10/13 * 10/13 so the same theory for A

C = 1/13 * 12/13 * 12/13 * 3 so similar to A however there are three ways you could achieve it (ie draw the Ace as first, second or third card) so you triple your chances

D = 1/4 + (3/4 * 1/4) + (3/4 * 3/4 * 1/4) Similar to C but once you have achieved the goal of getting your spade the subsequent cards dont matter so hence you analyse the 3 different results separately.


All the above assumes there are no jokers in the deck