Question

There are nine differently-titled books on a shelf. Four books have red covers, while the other five have black covers. How many different arrangements of the books can there be, if

(a) there are no restrictions on the order in which the books are placed?

Is it 9! ?


(b) all the black-covered books must be together?

Is it 5! ?

(c) all the black-covered books must be together and all the red-covered books must also be together?

is it 2! ?

(d) black- and red-covered books must alternate?

is it 4!5! ?

Answers

Scott
looks good
simon
+852 90603039, whatsapp, i do homework for students.
simon
or 254540049, qq , i do homework for students.
Michael
Yep spot on

Related Questions