Does this function have any real roots?
Archives: Community Posts
Puzzle Prime is tirelessly looking all around the internet to find the very best puzzles and bring them all to puzzleprime.com.
Get Rich or Get Broke
You start with $20 and keep betting $1. What is the probability that you will get broke before you win $50? What is the expected number of bets until one of these 2 events happens?
Isosceles Triangle 80-80-20
That’s my favorite geometric problem from high-school days…
You are given an isosceles triangle ABC, ∠CAB = ∠ABC = 80°. Point D belongs to the side BC, so that AB = CD. Find the measure of angle ∠DAB.
Find the Differences
Here is a fun puzzle, created by Hot Spring World. There are 8 differences between the pictures below. Can you find them all?
Creepy Beasties, Inc.
Halloween is coming up, so here’s a good logic puzzle. Can you determine who’s who based on the story I give below?
At Creepy Beasties, Inc., three of the most dreaded animals, a spider, a snake, and a rat, sat in their boardroom in silence while they awaited their boss. Then, Mr. Spider broke the silence.
“Isn’t it odd that our surnames match our species, yet none of our surnames match our own?”
The snake replied, “Yeah, but does anybody give a crap?”
They sat in silence again.
Number of Local Minimums
100 real random numbers between 0 and 1 are written in a row. What is the expected number of local minima in the row, i.e. numbers which do not stand next to a smaller number?
Five Heads, Five Tails
If you throw a fair coin 1000 times, what is the expected number of occurrences of 5 heads followed by 5 tails?