PST Counting and nCr prob

Front

What is the formula for combinations (nCr)?

Back

nCr = n! / (r! * (n - r)!) where n is the total number of items, and r is the number of items to choose.

Front

What is the formula for permutations (nPr)?

Back

nPr = n! / (n - r)! where n is the total number of items, and r is the number of items to arrange.

Front

How do you calculate the probability of selecting a specific combination of items?

Back

Use the formula: P = (number of favorable outcomes) / (total number of outcomes). For combinations, use nCr.

Front

What does 'n' represent in the context of combinations and permutations?

Back

'n' represents the total number of items available for selection.

Front

What does 'r' represent in the context of combinations and permutations?

Back

'r' represents the number of items to be selected or arranged.

Front

How many ways can you choose 3 items from a set of 5?

Back

5C3 = 10 ways.

Front

If you have 8 kittens and 12 puppies, how many ways can you choose 2 puppies and 3 kittens?

Back

12C2 * 8C3 / 20C5.

Front

What is the total number of outcomes when tossing a coin and picking a card from a standard deck?

Back

104 outcomes (2 outcomes for the coin and 52 for the card).

Front

How do you calculate the number of ways to arrange items in a line?

Back

Use permutations: nPr = n! / (n - r)!.

Front

What is the difference between combinations and permutations?

Back

Combinations do not consider the order of selection, while permutations do.