Question

There are several sets of different numbers which can be chosen from {0,1,2,3,4,5,6,7,8,9}. How many of these sets contain any 2 numbers? PLS HELP I'M REALLY STUCK AND DON'T JUST STEAL THE POINTS PLEASE

Answer 1

90

Explanation:

it is 90 because in the first slot there can be any 10 numbers and in the second slot the set can contain any of the remaining 9 numbers and then we can multiply these two numbers together to find the total amount of sets.

hope this helps :)

Answer 2

45 different sets

Explanation:

There are 10 numbers in {0,1,2,3,4,5,6,7,8,9}.

We are looking for a combination since order doesn't mater

There are 10 options for the first number

We have chosen 1

Now there are 9 numbers

10*9

But since order doesn't matter, we divide by 2

The set {1,2} is the same as the set {2,1}

90/2 = 45