sets

[sujoy]

sir the prob is
'A' is a set of naturaL NOS from 1 to 10, .'B' is a subset
consisting of coprimes's,set---- how many such sets are possible
in'B'?
regards
Sujoy

 

[pka]

Leave 10 out! Consider {2,4,8}, {3,9}, {5}, {7}.
Now to have copimes we must chose at least two coming from different sets.
Say: {2,9,7} or {5,7}. How many such sets are there?

On the other hand, do you mean “how many pairs of coprimes are there?”
If so, then count the ordered pairs.

Now in either case, go back and see where you can ‘add’ 10.

 

[sujoy]

Sir
I meant how manyb such sets are there
thanks
regards
sujoy

 

[pka]

Do you read English well?
That is the answer I gave you.
It was not clear if you wanted subsets in which all menbers ar coprines, (that is what I gave you to work out), or did you want all the pairs of coprimes?

 

[sujoy]

:!:Sir I am sorry
I never really mean to tease you
with regards
sujoy