Test your Psychic powers! + Understand the Odds of guessing 20 coin tosses correctly in a row

By | June 15, 2012

Are you psychic? Do you understand probability? What are the odds of guessing 20 coin tosses correctly?

The odds of guessing one fair coin toss correctly are 50/50. You’d be right 1/2 of the time. (50%)

The odds of guessing the second coin are still 50/50, but for the odds of being correct both times in a row, you’d multiply the two probabilities. So, you’d get 0.5 * 0.5 = 0.25. You would guess both correctly 1/4 of the time (25%)

For three coin tosses, the odds of guessing all three correctly are 0.5 * 0.5 * 0.5 = 1/8 or 12.5%. Looked at another way, there is an 87.7% chance that you could not guess three in a row.

For 10 coin tosses, you would guess all 10 correctly only 0.1% of the time. In other words, the 99.9% of the time you would not do this.

For 20 coin tosses, the odds of guessing all 20 correctly are 0.0001%, or 1 in 1 million 48 thousand five hundred seventy six. You are more likely to be struck by lightning this year than to guess 20 coins in a row. It could happen, but the odds are over 1 million to one against that happening.

For comparison: According to NOAA, the odds of being struck by lighting are 1 in a million (1,000,000) in any given year. If you live to be 80 years old, the odds increase to 1 in 10,000 that you will be struck by lightning. In other words, guessing 20 coin tosses correctly is about as likely as getting struck by lightning some time in your life. Very un-likely! 1 in a million!

Try this psychic coin guessing demo:

http://www.stat.tamu.edu/~west/applets/psychictest.html

Psychic Test Demonstration.

For my guesses, I got 8, 12, 10 correct when I did 20 in a row. I never could get 13 or 14 correct out of 20 guesses. Let me know how you do!

Here’s my chart you can use with the above test to see if you are amazing at either guessing correctly, or missing:

Odds of guessing: % Probability Odds (1 in … )
20 OMG!!! 0.0001% 9.53674E-07 1,048,576
19 REALLY?? 0.0019% 1.90735E-05 52,429
18 AMAZING 0.0181% 0.000181198 5,519
17 WOW 0.1087% 0.001087189 920
16 WOW 0.4621% 0.004620552 216
15 STRANGE 1.4786% 0.014785767 68
14 STRANGE 3.6964% 0.036964417 27
13 STRANGE 7.3929% 0.073928833 14
12 RANDOM 12.0134% 0.120134354 8
11 RANDOM 16.0179% 0.160179138 6
10 RANDOM 17.6197% 0.176197052 6
9 RANDOM 16.0179% 0.160179138 6
8 RANDOM 12.0134% 0.120134354 8
7 STRANGE 7.3929% 0.073928833 14
6 STRANGE 3.6964% 0.036964417 27
5 STRANGE 1.4786% 0.014785767 68
4 WOW 0.4621% 0.004620552 216
3 WOW 0.1087% 0.001087189 920
2 AMAZING 0.0181% 0.000181198 5,519
1 REALLY?? 0.0019% 1.90735E-05 52,429
0 OMG!!! 0.0001% 9.53674E-07 1,048,576

My purpose is to be able to apply this to other things, such as testing other paranormal claims.

To prove something works and is not just by chance then, I’d want to test it 20 times. If there is a yes/no option, I’d expect about 8 to 12 hits correct by pure chance. Notice that the odds of getting 16 correct are 216 to 1, but the odds of 19 correct are 52,429. Quite a difference!

0 thoughts on “Test your Psychic powers! + Understand the Odds of guessing 20 coin tosses correctly in a row

  1. Bob Reeves

    When I was 8 years old, a very intelligent 13 year old friend asked me to guess a coin toss and I got it right over 30 straight times. It was about 32 to 34 when he stopped and said do you know what you just did. I said I got it right. He said do you know what the odds of doing that are. I said what are odds. Re said the chance of doing that are one n a million or more.

    At 19, when I was in college taking an intro to psychology, I was required to participate in an experiment ?? where they turned on a yellow light and you then had a few specified seconds to decide if the next light would be red or green. I was correct 162 out of 200. The testers looked at and question me as if I was from outer space. I never knew the purpose of the test.

    Later at 27 studying for the bar exam, I relaxed by trying to cut aces out of a deck and got to the point I could do it at about 80% and when I missed an ace was usually right next to the card I cut.

    About that time I went to a charity gambling event and found I could guess red black on roulette at about 90%.

    Then for some reason I got spooked . scared and quit doing any of this for decades. A few years ago I relaxed and tried cutting aces again/ After a lot of failures, I finally got to 50%. I decide to teach it to my 16 year old son and he quickly got better then me. On day he told me to show him any card in the deck and then shuffle and cut as many times as I wanted. I did it many times out of his site and put the deck down on a table. He successfully cut the3 of clubs.

    I have always had good intuition. Today I was wondering the odds on a coin toss 30 times and found your website.

  2. Seamus Maguire

    I regularly correctly guess 20 coins straight in a row, I found your website when looking up the odds. I usually stop at 20 because I freak myself or others out!!

Leave a Reply