Posted by **Lisa** on Saturday, January 19, 2008 at 10:59pm.

For MAMMALS, find the munber of:

a) 7-letter words

b) 7-letter word beggining with MA

c) 4-letter words

i) all letters different

ii) 2 letters same,2 different

iii) 2 pairs same letters

iv) 3 letters same

- data management -
**Damon**, Sunday, January 20, 2008 at 1:15pm
I am not doing the problem for you but perhaps I can give you an idea.

Let's see. I have to work with

M M M A A L S

If all letters were different the answer would be 7!, but they are not.

Let me try a simpler example

Say

A A B B

A B A B

A B B A

B A A B

B B A A

B A B A Hmm six of them, not 4!

Looks like permutations of 4 items divided by permutations of 2 As divided by permutations of 2 Bs

4!/(2!*2!) = 4*3*2 /( 2*2) = 6

Let's try it with 3 As and 1 B

A A A B

A A B A

A B A A

B A A A Is that 4!/(3!*1!) ?

4*3*2 /(3*2*1) = 4, sure enough.

## Answer this Question

## Related Questions

- Data Management - For PLANETS, find the number of : 4-letter words which must ...
- History - Even though I asked this before, can you please help me with this and ...
- geometry - In the English alphabet, there are 7 capital letters that look the ...
- Maths - A word made by writing the seven letters used to spell "EXAMPLE" in some...
- Counting and Probability - How many 2-letter "words" consist of two different ...
- HSPA Prep - Marybeth is trying to remember her 4-letter password. All she ...
- Geography - im doing this geography crossword. could you help me figure out what...
- Combinations - Anna was opening a new restaurant, so she went to the sign store ...
- Geometry - Ok i have a crossward puzzle and dont know some of the vocab. Here is...
- Socials Crosswords - Canada and the Twenties... New form of signage? It's 4 ...

More Related Questions