what is the # of possibilities of buying 2 CD's from 10 that are on sale?
To find the number of possibilities of buying 2 CDs from a selection of 10, we can use the concept of combinations.
To calculate the number of combinations, we use the formula:
C(n, k) = n! / (k!(n-k)!),
where n is the total number of items to choose from and k is the number of items we want to select.
In this case, we have a total of 10 CDs to choose from (n = 10) and we want to select 2 CDs (k = 2). Plugging these values into the formula, we get:
C(10, 2) = 10! / (2!(10-2)!)
= 10! / (2!8!)
= (10 * 9 * 8!) / (2! * 8!)
= 10 * 9 / 2!
= 10 * 9 / 2
= 90 / 2
= 45.
Therefore, there are 45 different combinations of buying 2 CDs from a selection of 10 CDs that are on sale.