Noobs Weekly: Release II

Week 2: Infinite Quarter Sequence

You are wearing a blindfold and thick gloves. An infinite number of quarters are laid out on a table of infinite area. 20 of these quarters are tails and the rest are heads. How can you can split the quarters into 2 piles where the number of tails quarters is the same in each? You are allowed to move the quarters and to flip them, but you can never tell what state a quarter is currently in.

#Riddles #NoobsWeekly

Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

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Math	Appears as
Remember to wrap math in `$` ... `$` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$

Comments

Take 20 of the quarters, flip them over and put them in one pile. The other coins go into one infinite pile. If there were $x$ tails among the finite pile when picked, there will be $20 - x$ tails in the infinite pile. As all 20 quarters that were picked have been flipped over, the finite pile will also have $20 - x$ tails. $\blacksquare$

Tan Li Xuan - 6 years, 8 months ago

@Michael Mendrin Where's your comment gone? I recall you posted a comment here too.

Tan Li Xuan - 6 years, 8 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$