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KS, why wouldn't the prob of the thousands digit be 5/9 ? Because 0 cannot be chosen here. I've seen this applied to other problems as well. Thoughts?

Thanks

If N=10,000 then the P for the thousands digit is 5/10 , since 00001 is a valid number (equal to 1).

If N=5000 then you don't need the P of the thousands digit at all (since its equal to 1).

Can you give me an example for other the problems you saw ?

I'm still lost...i still dont understand why n=10,000 with working out the problem with the thousandth digit. Killer Squirrel, you said If N=10,000 then the P for the thousands digit is 5/10 but i thought N=5000 with the 5/10.

Sorry mate! if you dont mind could you (or anyone else for that matter) spell this out nice and easy for a poor fool like myself?

In a set of numbers from 100 to 1000 inclusive, how many integers are odd and do not contain the digit "5"?

a. 180 b. 196 c. 286 d. 288 e. 324 --------- My solution, using the probability method:

N = 1000 - 100 = 900 P = (8/9)*(9/10)*(4/10) = 288/900

N*P = 900*(288/900) = 288 D. ----------

For the hundreds digit I've used 8/9. Wouldn't you use the same thinking for this question and use 5/9 ?

This problem can be solved in this way :

N = 1000

P = 8/10*9/10*4/10 = 288/1000

N*P = 288

or it can be solve as you solved it.

The main difference in this problem from the problem we discussed earlier is that in this case you cannot use P = 1 for the hundreds digit since this problem don't allow you to use five in the hundreds digit.

If you could use five then the P for the hundreds digit was 9/9 = 1 and you could just ignore it (the only number you can't choose is 0).

Last edited by KillerSquirrel on 15 Nov 2007, 11:55, edited 2 times in total.

KS, why wouldn't the prob of the thousands digit be 5/9 ? Because 0 cannot be chosen here. I've seen this applied to other problems as well. Thoughts?

Thanks

If N=10,000 then the P for the thousands digit is 5/10 , since 00001 is a valid number (equal to 1).

If N=5000 then you don't need the P of the thousands digit at all (since its equal to 1).

Can you give me an example for other the problems you saw ?

I'm still lost...i still dont understand why n=10,000 with working out the problem with the thousandth digit. Killer Squirrel, you said If N=10,000 then the P for the thousands digit is 5/10 but i thought N=5000 with the 5/10.

Sorry mate! if you dont mind could you (or anyone else for that matter) spell this out nice and easy for a poor fool like myself?

thanks!

Read the following attachment - If you are still lost PM me.