Day 2: Basic Probability Puzzles #1

Objective

In this challenge, we practice calculating probability.

Task

In a single toss of 2 fair (evenly-weighted) dice, find the probability of that their sum will be at most 9.

Answer : 5/6

Day 2: Basic Probability Puzzles #2

Objective

In this challenge, we practice calculating probability.

Task

For a single toss of 2 fair (evenly-weighted) dice, find the probability that the values rolled by each die will be different and their sum is 6.

Answer : 1/9

Day 2: Basic Probability Puzzles #3

Objective

In this challenge, we practice calculating probability.

Task

There are 3 urns: XX, YY and ZZ.

Urn XX contains 4 red balls and 3 black balls. Urn YY contains 5 red balls and 4 black balls. Urn ZZ contains 4 red balls and 4 black balls. One ball is drawn from each urn. What is the probability that the 33 balls drawn consist of 2 red balls and 1 black ball?

Answer : 17/42

Day 2: Basic Probability Puzzles #4

Objective

In this challenge, we practice calculating probability.

Task

Bag1 contains 4 red balls and 5 black balls. Bag2 contains 3 red balls and 7 black balls. One ball is drawn from the Bag1, and 2 balls are drawn from Bag2. Find the probability that 2 balls are black and 1 ball is red.

Answer : 7/15