Most US College Students Cannot How Many Holes Does A Straw 2 days ago   07:14

MindYourDecisions
To complete a job, it takes: Alice and Bob 2 hours, Alice and Charlie 3 hours, and Bob and Charlie 4 hours. How long will the job take if all 3 work together? Many, many US college students set up the equations incorrectly and get the wrong answer. Can you solve it? Watch the video to understand the correct method and answer.

*Small correction: At 2:19 I incorrectly said "four fifths" and meant to say "four point five."

My blog post for this video
https://wp.me/p6aMk-5h1

Sources
Toom, Andrei. "A Russian teacher in America." Journal of Mathematical Behavior 12.2 (1993): 117-139. See the "Tom, Dick, and Harry working together problem" (page 134 in text). https://faculty.utrgv.edu/eleftherios.gkioulekas/OGS/Misc/ARUSSIAN.PDF

Jerome Dancis, Associate Professor Emeritus, University of Maryland, Algebraic word problems. www.math.umd.edu/~jnd/Algebraic_word_problems.pdf

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Comments 4335 Comments

CQUNC
4.5 is now pronounced "four fifths" (2:19).
Dazzadaman
Charlie really doesn't seem to be much help...
_ annoyed
here, resistance is not futile
jablue
I'm a US college student. I solved it. My peers solved it without much problem either. I wouldn't say we're good representatives of the average, but this just wasn't hard. High school level for the worst states, elementary school for the better ones. Why wouldn't most US college students be able to solve this again?
Matyas Marousek
It's 110, 769... minutes (= 6 646, 15 seconds)
apazeia
So which one is the Millennial?
1969nitsuga
Maybe Alice is doing nothing... A nail job or cofee... Or Bob is doing weed at the bath...
1969nitsuga
The answer is wrong because it is A+B=2(A/C+B/C)=1.6×60 min.=96=1hr 36mins.
Get Rekt
4.5 is correct because they might have social anxiety
Damenra Rana
30 min.
Tibo Louis
I made the same mistake...
Humble Hermit
I thought of it as how many jobs can they do in 12 hours (lcm), solved, added all 3 together, then put that under 12 to convert back to hours per job.
srikar sreekar
2(a+b)=3(a+c)=4(b+c) =x
A+b+c = 13/24 x.
X = 24/13 (all together )
AJ02
Your name is Presh Talwalkar
Sai Vinod
4/30 hrs
Kashish Attractions
Yes i did it but by a different method
Joseph Stalin
Have you ever done creative writing
Joseph Stalin
4.5 hours is the max, and an hour is the minimum. In a work place, as the question frames, a hard time is nonexistent.
Melis Derveni
There are 2 things you dont know in this problem, not only the time but the pace of each worker
Roger didit
Coefficient? Factor out? Hire one Mexican named Pedro. Pedro gets the job done in one hour. Problem solved!!
Add Reply

How Many Holes Does A Straw Most US College Students Cannot 2 days ago   04:21

This question has generated a lot of debate online. BuzzFeed's video has 450,000+ views already. But the question has a mathematical interpretation with a correct answer: in topology, how many holes does a straw have? I explain and animate the answer in the video. It's great to see topology go viral!

My blog post for this video
https://wp.me/p6aMk-5sB

BuzzFeedVideo
https://up-tube.com/upvideo/J0gLEIDiXoZ

Drinking Straws: How Many Holes? Kevin Knudson, professor of mathematics at the University of Florida
https://www.forbes.com/sites/kevinknudson/2018/01/29/drinking-straws-how-many-holes/

2016 Nobel Prize in Physics
https://www.nobelprize.org/nobel_prizes/physics/laureates/2016/

If you like my videos, you can support me at Patreon:
https://www.patreon.com/mindyourdecisions

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If you buy from the links below I may receive a commission for sales. This has no effect on the price for you.

My Books
"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 3.8/5 stars on 31 reviews)
http://amzn.to/1uQvA20

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 4.6/5 stars on 3 reviews)
http://amzn.to/1o3FaAg

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews.
http://amzn.to/1GhUUSH

"Math Puzzles Volume 2" is a sequel book with more great problems. (rated 4.3/5 stars on 4 reviews)
http://amzn.to/1NKbyCs

"Math Puzzles Volume 3" is the third in the series. (rated 3.8/5 stars on 5 reviews)
http://amzn.to/1NKbGlp

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)
http://amzn.to/1LOCI4U

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 4 reviews)
http://amzn.to/18maAdo

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 3 reviews)
http://amzn.to/XRm7M4