Three 0's and two 1's make 5, not 10, digits. Also, |A union B| = |A| + |B| - |A intersection B|. I think you have "and" and "or" switched.How many elements of A have exactly three o's and two 1's?
I have the following question and struggling:
let A be the 10-digit decimal integer, that is
How many elements of A have exactly three o's and two 1's?
So i need to use p(a and b)= p(a) + p(b) - p(a or b)
Just struggling to find how many elements there are with exactly what is needed so i can apply it to the equation
many thanks in advance.
Select those places . Those can be filled in 8^5 different ways.
From the remaining five places choose two, , into which the 1ís go. The zeros go into the remaining places.
Now just multiply.
Edit: Note the and.