A person adopts four pets, and each pet is either a cat (c) or a dog (d), with both being equally likely. List all possible outcomes in the sample space.
What is the probability of getting three cats and one dog (in any order)?

Sample space: {ccdd, ccdd, cddc, dcdc}

Probability: $0.15$

Sample space: {dccd, ccdc, cdcc, dccc, ddcc}

Probability: $0.50$

Sample space: {cccd, ccdc, cdcc, dccc}

Probability: $0.25$

Sample space: {cc, dc, cd, dd}

Probability: $0.75$