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Core Connections Algebra 2, 2013 View details

1. Section 10.1

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Exercise 21 Page 506

a On Andrea's combination lock, the order of the chosen digits for the combination matter. This means we are looking for the number of permutations when selecting

5

digits from a set of

10 .

To calculate this we will use the following formula.

_{n} P_{r} = \frac{n !}{( n - r ) !}

Since we have ten digits and want to create a group of five, we have

n = 10

and

r = 5

_{10} P_{5} = \frac{1 0 !}{( 1 0 - 5 ) !}

To calculate this, we can use our built in permutation-function on our graphing calculator. First we enter the number of digits we have to choose, from which is

10 .

Next, push the $MATH$ button, scroll to PRB, and choose the second option. Having chosen nPr, we must also enter the number of digits in the lock.