OpenStudy (rock_mit182):

License plate numbers In a certain state, automobile license plates start with one letter of the alphabet, followed by five digits(0,1....9) . Find how many different license plates are possible if (a) the first digit following the letter cannot be 0 (b) the first letter cannot be O or I and the first digit cannot be

OpenStudy (rock_mit182):

(b) the first letter cannot be O or I and the first digit cannot be 0

OpenStudy (rock_mit182):

@bibby

OpenStudy (bibby):

(a) the first digit following the letter cannot be 0 that means there are 26 possibilities in the first thing, 9 in the second, and 10 for the rest. multiply it out

OpenStudy (rock_mit182):

is this a combination c(n,k) = n!/(n-k)!k! how do i plug the values

OpenStudy (bibby):

I don't think it's combinations. It's just simple probability so just multiplication

OpenStudy (rock_mit182):

well i don't know then how you get the answers

OpenStudy (bibby):

ok, picture a generic license plate.|dw:1397685386828:dw|

OpenStudy (rock_mit182):

I'm lost with this one , cause I'm not good on probability at all

OpenStudy (bibby):

the thing on the bottom represents the possibilities, the thing on top is the number of possibilities just multiply across

OpenStudy (rock_mit182):

for the first one would be : 26 (letters) * 9(numbers)* 9 to the 4th power ?

OpenStudy (bibby):

times 10 to the fourth remember that you can't have 0 in the first digit

OpenStudy (rock_mit182):

im sorry the last 10 to the 4 th

OpenStudy (rock_mit182):

oh now i totally get it

OpenStudy (rock_mit182):

well i was confused cause the combination forlmula

OpenStudy (bibby):

the combinations are used when you have to choose. That's a terrible explanation but google will serve you better.

OpenStudy (rock_mit182):

2. 26-2( T letters - I and O) * 9 ( T digits - digit 0) * 10 to the 4th ( the other possible digits withouth restrction)

OpenStudy (rock_mit182):

well i don't know about that but you have been very helpfull

OpenStudy (rock_mit182):

Thanks a lot @bibby ;)

OpenStudy (bibby):

that's correct (b)

OpenStudy (rock_mit182):

Thanks .)