Three hundred million eight hundred thousand
The sample % of these two populations would be 100/size (of student body at each school) x 100 so this would compare the two student bodies preferences for the particular type of candy bar. However, the actual % of the whole student body at each school would be a factor also. If the high school only had 200 students then this would be 50% representative but if the middle school had say 500 students this would only be 20% representative so this would have to be taken into account too. It might be more representative to have the same % of the student bodies respectively for the sample.
The first letter can be any one of 8. For each of those . . .
The second letter can be any one of the remaining 7. For each of those . . .
The third letter can be any one of the remaining 6. For each of those . . .
The fourth letter can be any one of the remaining 5. For each of those . . .
The fifth letter can be any one of the remaining 4.
The total number of possibilities is (8 x 7 x 6 x 5 x 4) = <em>6,720</em> .
(That's 8! / 3! .)
Note:
If you're allowed to use the same letter more than once,
then there are 8 choices for each of the 5 letters.
The total number of possibilities then is (8 x 8 x 8 x 8 x 8) = 32,768 .
(That's 8⁵ or 2¹⁵ .)
