It’s the Friday Puzzle!

13

Solution on Monday.

Imagine a test with 26 questions.  When you get a question wrong you are deducted 5 points.  When you get a question right you are given 8 points.  If you answered all of the questions, and had a final score of 0 points, how many questions did you answer correctly?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

13 comments on “It’s the Friday Puzzle!”

1. kroketje says:

dohhh!! It’s your first time, isn’t it?

2. Stan says:

Wow isn’t there a rule to not post answers??? But Richard, I do thank you for letting us post responses.
I had to resort to using algebra on this one. It’s actually remarkable about rarely one needs to use algebra in one’s normal life, but it is still a good thing for logical thinking. It took about 30 seconds to do that algebra.

3. curtisfrye says:

15 seconds; key was realizing what the multiplication results had to look like.

4. VicinCA says:

I got it by simple trial and error on the second try. About 10 seconds.

5. Percy Veerance says:

Imagine a Friday Puzzle with one question. When you post the answer before Monday you are deducted 5 points …….

6. […] It’s the Friday Puzzle! « Richard Wiseman. […]

• A Non says:

Why?

7. Eddie says:

Love it. Richard tentatively puts back the comments… and the first comment after the long period of imposed penance is……. a spoiler………………………..brilliant.

8. Steve Jones says:

Not much room for lateral thinking with this problem, which is a bit of a shame.

Not so fast there, Steve, what if you do not answer some of the questions?

• Gabby Bollard says:

Read the question ” If you answered all of the questions, …”

9. I Luv Spoilers says:

I preferred it when we used to post our spoilers on the last thread before Friday.
I think that Richard should ban comments on Friday.
20 seconds to do the algebra

10. Anonymous says:

Why did you post the answer?