## mathmath333 one year ago What the does this statement means

1. mathmath333

\large \color{black}{\begin{align} & \normalsize \text{ If there are three things to do.}\ \hspace{.33em}\\~\\ & \normalsize \text{ M ways of doing first thing.} \hspace{.33em}\\~\\ & \normalsize \text{ N ways of doing second thing.}\ \hspace{.33em}\\~\\ & \normalsize \text{ P ways of doing third thing.}\ \hspace{.33em}\\~\\ & \normalsize \text{When the pieces of work are mutually exclusive ,there are }\hspace{.33em}\\~\\ & M+N+P\ \normalsize \text{ways of doing the complete work. }\hspace{.33em}\\~\\ \end{align}}

2. ganeshie8

suppose you have M blue shirts, N white shirts P black shirts

3. mathmath333

ok

4. ganeshie8

how many ways can you go out to a movie with your girlfriend ?

5. mathmath333

3 ways

6. mathmath333

*i m a monk by the way

7. ganeshie8

Ahh wait, lets also assume that all shirts are different

8. ganeshie8

the M blue shirts are different they are not uniforms, your girlfriend can tell the difference..

9. mathmath333

ok like M blue shirts of different sizes ?

10. ganeshie8

yes, different size/shades etc... consider they are different

11. mathmath333

m*n*p

12. ganeshie8

nope, let me ask u a q how many total shirts do you have ?

13. mathmath333

m*blue+n*white+p*black

14. ganeshie8

right, so you can pick any "one shirt" from the available "m+n+p" shirts

15. ganeshie8

you just have "m+n+p" choices because you can't wear more than one shirt at the same time

16. ganeshie8

lets do another example maybe

17. mathmath333

what is mutually exclusive

18. ganeshie8

"mutually exclusive" is same as "any two things cannot happen at the same time"

19. mathmath333

ok

20. ganeshie8

read this quick and let me know once ur done https://www.mathsisfun.com/data/probability-events-mutually-exclusive.html

21. mathmath333

okk done

22. ganeshie8

you went to a restaurant for breakfast and saw the menu

23. ganeshie8

it shows : 3 different types of north indian items 5 different types of south indian items how many choices do you have for ordering "one" item for breakfast ?

24. mathmath333

8

25. ganeshie8

Correct. so you can see the difference, when to multiply and when to add

26. ganeshie8

lets do one more example

27. ganeshie8

you also have coffee/tea during breakfast so, here comes the question :

28. ganeshie8

you went to a restaurant for breakfast and saw the menu : breakfast items : 3 different types of north indian items 5 different types of south indian items hot drinks : 6 different types for coffee 2 different types for tea you want to order "one" breakfast item and "one" hot drink, how many ways can you order them ?

29. mathmath333

64 ?

30. ganeshie8

how ?

31. ganeshie8

64 is correct, just see if u can explain how

32. mathmath333

3*6+3*2+5*6+5*2=64

33. ganeshie8

that is one way

34. ganeshie8

 breakfast items : 3 different types of north indian items 5 different types of south indian items hot drinks : 6 different types for coffee 2 different types for tea 

35. ganeshie8

total choices for breakfast = 3+5 = 8 total choices for hot drinks = 6+2 = 8 since for each breakfast item that you pick, there are again 8 more choices for hot drink, the total number of ways that you can have breakfast AND hot drink is 8*8 = 64

36. mathmath333

ok