How many ways can an IRS auditor select 3 of 11 tax returns for an audit?
A)1331 B)6 C)990 D)165
My answer is: 990.
Is this correct?
Thanks.
No it's not. You haven't considered the fact that the order in which he takes the audits doesn't matter. So e.g. the combination 1-2-5 would be the same as 5-1-2.
So would it be 165?
Correct.
He can choose from 11, 10 and 9 returns, which make 990 choices. As noted by Christiaan, the order is not important. So divide by 3! (for 3 returns) to make 990/6=165.
How do I show this math problem 990
Divided by 6.
To find the number of ways an IRS auditor can select 3 tax returns out of 11 for an audit, we can use the combination formula.
The combination formula, denoted as "nCr," calculates the number of ways to choose r items from a set of n items, without regarding the order.
In this case, we want to find the number of ways to select 3 tax returns out of 11. The combination formula is defined as:
nCr = n! / (r!(n-r)!)
where "!" represents the factorial function.
Using this formula, we can calculate:
11C3 = 11! / (3!(11-3)!)
= 11! / (3! x 8!)
Calculating the factorials:
11! = 11 x 10 x 9 x 8!
3! = 3 x 2 x 1
Substituting these values into the equation:
11C3 = (11 x 10 x 9 x 8!) / (3 x 2 x 1 x 8!)
= (11 x 10 x 9) / (3 x 2 x 1)
= 990
So, the correct answer is indeed 990 (option C). Good job!