perms and combs (1 Viewer)

[maths lover]

how many arrangements can be made by the letters of the word definition
a)if the letters i don not occupy the first and last positions.
b)if the letters i are together
im pretty sure that b is easy im just having troubles getting a. i was pretty sure my working was correct but didnt match with the answer so yeah. thanks

 

[funnytomato]

http://community.boredofstudies.org/showthread.php?t=263799

 

[maths lover]

woops thanks