How to use replacement in probability

Step-by-step explanation:

Replacement means the probability of each trial is the same (the trials are independent).

For example, let's say you have a standard deck of 52 cards, and you want to find the probability of drawing a queen card twice.

There are 4 queens, so the probability on the first draw is 4/52.

You then replace the queen, so there are still 4 queens in the deck.  So the probability on the second draw is still 4/52.

The total probability is the product: 4/52 × 4/52 = 1/169

If you didn't replace the queen after the first draw, there would have been 3 queens in the deck, and the probability on the second draw would have been 3/52.

Mrs. Stern washed more

laundry still needs to be washed.

Step-by-step explanation:

Total amount of laundry:

of the laundry still needs to be done.

Mrs. Stern washed of the laundry.

Her son washed of the laundry.

Mrs. Stern washed more laundry than her son.