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Comment on Rewriting Questions
Question link: https:/
Question link: https://gmatclub.com/forum/an-integer-between-1-and-300-inclusive-is-cho...
We know that 2^8 = 256 and 2^9 = 512
So, if the base is 2, we need only consider exponents up to 8 (since we're looking for powers that are less than 300).
Similarly, 3^5 = 243 and 3^6 = 729.
So, if the base is 3, we need only consider exponents up to 5
As you can see 8 is the biggest possible exponent that yields a power that is less than 300.
Does that help?
Hi Brent, Thanks for the
In question: https://gmatclub.com/forum/if-3-different-numbers-are-selected-from-the-first-8-prime-numbers-wh-277804.html
Why is this approach wrong: No of possible outcomes 8c3. and to select the number of ways to have the number 2 in the sum be = 1 (Since picked 2 first) x 7 (number of ways to pick first odd) x 6 (number of ways to pick second odd prime). Therefore probability = 42/56 = 3/4
Thanks for your help
Question link: https:/
Question link: https://gmatclub.com/forum/if-3-different-numbers-are-selected-from-the-...
With your calculations for the numerator (the number of ways to get a n odd sum), you're counting several outcomes more than once.
Using your method, selecting 2 then 11 then 7 is consider different from selecting 2 then 7 then 11.
Since the order in which we select the other two primes doesn't matter, we can use combinations.
Once we've selected the necessary 2, we must select two more primes from the 7 remaining primes.
We can do this in 7C2 ways.
So the probability = 7C2/8C3 = 21/56 = 3/8
Hi Brent,
In the question https://gmatclub.com/forum/a-certain-business-school-has-500-students-and-the-law-142199.html, I took two scenarios where we select once student sibling from business school and then selecting that student's sibling from the law school and then do it first with the law school and follow up with business school.
My answer was 6/4000. Why are we considering just one scenario instead of both?
Question link: https:/
Question link: https://gmatclub.com/forum/a-certain-business-school-has-500-students-an...
Those two outcomes are identical.
For example, let's say that Bob and Ann are siblings, and that Bob is in Business School, and Anne is in Law School.
Selecting Bob from Business School and then Ann from Law School is the exact same outcome as selecting Ann from Law School and then Bob from Business School.
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