Unformatted text preview: the probability method.
One footnote on the concept of XX: I said that you can choose out of ten digits for the first X and out of ten
digits for the other X. This is not entirely true since 00 is not a valid integer (out of range) but 100 is also out
of range (XXX) so these two integers cancel out each other (you will see that this will give us a headache in
more complex problems). 1 How many integers between 324,700 and 458,600 have tens digit 1 and units digit 3?
Using the probability method we need to find the number of integers (N) so here N = 458,600 – 324,700 =
133,900 and now we need to figure out the probability (P). Since we have two digits XX for the tens digit and
units digit and the probability for the first X is 1/10 and the probability for unit digit of 3 is 1/10 then P =
1/10*1/10 = 1/100.
P*N = 1/100*133,900 = 1,339
And the answer is (E)
How many odd integers between 200 and 600 are there such that t...
View Full Document
- Fall '13
- Numerical digit, digit, 4-digit, 4 digits, probability method