Imagine an HIV test that is 95% accurate (false positive rate of 5%) and around 2% of the tested population is infected with HIV. What is the probability that you actually have HIV when your test comes back positive?
The name ABRAHAM can be changed into a word for a primitive musical instrument by replacing each letter with a different letter. The repeated letters (A is this case) must be replaced with the same replacement letter in the new word.
Ronald has a rare opportunity to meet the President of the United States. During his visit the president gives him a gift but tells Ronald he is never to sell it unless he sees the president again. Ronald consents, but the president dies later that year. Years later a man offers to buy the President’s gift for $1000. Ronald agrees and exchanges the gift for 20 crisp $50 bills. Did he keep his promise?
Yes. The president was Ulysses S. Grant, who died in 1885 and whose face has been on the $50 bill since 1913. He saw the president on the bills before he made the exchange.
A bookworm eats from the first page of an encyclopedia to the last page in a straight line. The encyclopedia consists of ten 1000-page volumes and is sitting on a bookshelf in the usual order. Not counting covers, title pages, etc., how many pages does the bookworm eat through?
On a book shelf the first page of the first volume is on the “inside”, so the bookworm eats only through the cover of the first volume, then 8 times 1000 pages of Volumes 2 – 9, then through the cover to the 1st page of Vol 10 for a total of 8,000 pages.
Note: The question asks how many pages, not how many sheets of paper.
Perform this calculation in your head, mentally adding the numbers as quickly as you can. Start with 1000 and add 40. Now add 1000. Add 30 to that, then add another 1000. Now add 20 to that result. Add another 1000 and finally, add 10 to that. What is the total?
A worm. Worms don’t have eyes or ears, but they can sense light and their bodies can detect vibrations in the ground. Fishers use worms as bait and the term bookwork is used for someone who loves to read.
Pencil lead. While modern pencils don’t contain lead, that’s still what we call the graphite compound. When real lead was used in pencils it was mined and nearly everyone has used a pencil at some point in their life.