## Online Course Discussion Forum

### MC I-A Counting and Probability Homework 4.20

Hi, Could you explain how to solve homework 4.20 in MC I-A Counting and Probability?

"How many total ways can you draw red cards and black cards from a standard deck of cards so that theblack cards appear consecutively in the card draw?"

There are four ways to grab the $5$ cards so that the $2$ black are consecutive: $BBRRR$, $RBBRR$, $RRBBR$, and $RRRBB$.

There are $26 \times 25 \times 26 \times 25 \times 24 = 10140000$ ways to grab the cards precisely in $BBRRR$ order. You can find the number of ways to grab the cards in the other three cases in a similar way.

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