Two cowboys live next door to each other and both have a corral for their cows in the back. One day they meet at the back of their homes, standing next to a wall dividing their corrals. The first cowboy gets to thinking and asks his neighbor for a cow so he can double his herd. The other cowboys replies, “That’s fine by me partner, cuz then we’ll have the same number of cows?” How many cows does each cowboy own?
A variation of this brain teaser includes laser printers (they were invented by Gary Starkweather) and bulletproof vests (invented by Casimir Zeglen using silk, though modern vests use Kevlar, so it’s halfway right).
I hesitated to add this because it’s poorly worded, ambiguous and the answer could be almost anything. I prefer teasers with a single answer, but there you go.
If you came up with a different answer and can explain how you did it, don’t think you’re wrong. It’s probably just as valid. Feel free to share yours in the comments.
My answer for the first number is 2.
Here’s how I got it.
The generic rule for a number in the sequence is: 2^(n – 1) + 1, where n is the position in the sequence.
Note: The teaser doesn’t specify the position of 17. In this case, it’s fifth.
Position 1: (so n = 1) is 2^(1 – 1) + 1 = 2
Position 2: 2^(2 – 1) + 1 = 3
Position 3: 2^(3 – 1) + 1 = 5
Position 4: 2^(4 – 1) + 1 = 9
Position 5: 2^(5 – 1) + 1 = 17
For the curious, the next 5 numbers of the sequence would be: