Show all of the possible three-digit numbers with distinct digest that can be made using the digits 4, 5, 6, 5, an 7. A counting tree may help.
How would I go about solving this problem??
I assume you mean. How many distict 5 digit numbers can be made with the digits 4,5,5,6,and 7
Well, for the first digit there are 5 numbers to choose from.
for the second there are 4 numbers and so on so this is
5*4*3*2*1 ways = 120 ways
However, there are 2 5's so there are really half this number because, for instance,
45567 is the same as 45567
so there will be 120/2 = 60 ways.
the more general formula for this is 5!/2!
The question asks for three digit numbers with distinct digits, (which I take to mean that we can't use both fives, and in which case the second five is irrelevant).
In that case, there will be 4 choices for the first digit, 3 choices for the second and 2 choices for the third.
24 possible numbers.
Yes I believe you are correct annon.
I guess I need new glasses. LOL
The second 5 appears to be irrelevent.
So you want 3 digit numbers using 4,5,6 and 7
There are 4 choices for the first digit, 3 for the second and 2 for the third - that makes
4*3*2=24
just as anon said :))