Author 
Topic 

raghu
Senior Member
USA
37 Posts 
Posted  09/04/2008 : 13:09:32

1. Superman and Batman(together) peel a bucket of potatoes in 20mts, superman and cinderella in 15 minutes and cinderella and Batman in 12 minutes. How long does it take superman to peel a bucket of potatoes? 2. How many 3 letter sequesnce can be made using letters in the word BOOKKEEPER? (for example 'OKO is acceptable; OPP is not acceptable).
Any help is appreciated. 


Subhotosh Khan
Advanced Member
USA
9116 Posts 
Posted  09/04/2008 : 14:10:11

quote: Originally posted by raghu
1. Superman and Batman(together) peel a bucket of potatoes in 20mts, superman and cinderella in 15 minutes and cinderella and Batman in 12 minutes. How long does it take superman to peel a bucket of potatoes? 2. How many 3 letter sequesnce can be made using letters in the word BOOKKEEPER? (for example 'OKO is acceptable; OPP is not acceptable).
Any help is appreciated.
Number 1 is a simple problem  what have done? Please share with us.
For #2
How many letters are ther in total  in BOOKKEEPER
How many B's, how many K's, How many R's....
If all the letters were different and  you were to choose three letteres  how many ways you could have chosen those?
Now work from there .. show some thoughts...



raghu
Senior Member
USA
37 Posts 
Posted  09/04/2008 : 14:20:47

1. s + B can do 1/20 of the job in 1 minute S + c can do 1/15 in 1 minute c + B can do 1/12 in 1 minute Adding all these 2(s + C + B) can do 720/360 of or s + c + b can do the whole job 1 1 minue. From here on I have no clue. as far as the second problem, I still don't have a clue. 


Subhotosh Khan
Advanced Member
USA
9116 Posts 
Posted  09/05/2008 : 11:44:48

For the second problem there are 10 letters and youare choosing 3 at a time.
If all the letters were different, you could have chosen _{10}P_{3} ways.
Now continue.... 



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