Math thread

[MickAK]

Here is something about exponents and how they work
https://www.khanacademy.org/math/alg...l-growth-decay
Here is a little about graphs
https://www.khanacademy.org/math/pre...-represent-dat
Here is a little about logarithms
https://www.khanacademy.org/math/alg...hmic-functions

Here is something about Interpolation and Extrapolation
https://www.youtube.com/watch?v=JI1Nvr294ps

Here is some real world data to have fun with the above information!
https://www.transportation.gov/sites...une%202019.pdf

Math is fun! Please post good data and learning resources ITT!

[0ddl0t]

Base Rate Fallacy

Denominator Neglect

[cmoore]

How many cartons are there in a case of the ass?

[Darth_Uno]

This thread is appropriate. My son recently had to find the perimeter of an object to the nearest .1". He and I came up with 29.9. I've run this 50 times and I still get that. The supposed correct answer is 30.4. If anyone can tell me where I'm wrong, it'd be much appreciated. FTR in construction I figure perimeters and areas every single day. I don't see where I'm wrong.

[trailrunner]

This thread is appropriate. My son recently had to find the perimeter of an object to the nearest .1". He and I came up with 29.9. I've run this 50 times and I still get that. The supposed correct answer is 30.4. If anyone can tell me where I'm wrong, it'd be much appreciated. FTR in construction I figure perimeters and areas every single day. I don't see where I'm wrong.

I get 29.8 (difference might be a rounding error).

Cut it in half horizontally, but don't do the semi-circle yet. Top half from L to R:

angled segment: 1.4*3=4.2 (alternately sqrt(3^2+3^2)=4.2)
vertical segment: 2
horizontal segment: 2
vertical segment: 2
total upper half without semi-circle: 10.2
total lower half without semi-circle: 10.2
semi-circle: 2*3.14*3/2=9.4

10.2+10.2+9.4=29.8

[0ddl0t]

This thread is appropriate. My son recently had to find the perimeter of an object to the nearest .1". He and I came up with 29.9. I've run this 50 times and I still get that. The supposed correct answer is 30.4.

29.9 is the correct answer.

Semicircle: (pi)d/2 ~= 9.4
Vertical segments: 8
Horizontal segments: 4
Angled segments: 2 × sqrt(a^2 + b^2) ~= 4.5
-----

29.9

[nycnoob]

If you know some advanced mathematics you might enjoy these:


3Blue1Brown

https://www.youtube.com/channel/UCYO...17AJtAw/videos


Mathologer

https://www.youtube.com/channel/UC1_uAIS3r8Vu6JjXWvastJg/videos

[nycnoob]

The Most IMPORTANT Video You'll Ever See

https://www.youtube.com/watch?v=DZCm2QQZVYk


This is the famous lecture by Albert Bartlett "Arithmetic, Population and Energy"
Which is all about the exponential function and why it is so hard to reason
about.

[cmoore]

You drive half way to work and average only 15 mph due to heavy traffic. How fast must you drive the remaining distance to work to average 30 mph for the entire trip?

a) 45 mph

b) 55 mph

c) 60 mph

d) Faster than the speed of light

[Darth_Uno]

I get 29.8 (difference might be a rounding error).

Cut it in half horizontally, but don't do the semi-circle yet. Top half from L to R:

angled segment: 1.4*3=4.2 (alternately sqrt(3^2+3^2)=4.2)
vertical segment: 2
horizontal segment: 2
vertical segment: 2
total upper half without semi-circle: 10.2
total lower half without semi-circle: 10.2
semi-circle: 2*3.14*3/2=9.4

10.2+10.2+9.4=29.8

29.9 is the correct answer.

Semicircle: (pi)d/2 ~= 9.4
Vertical segments: 8
Horizontal segments: 4
Angled segments: 2 × sqrt(a^2 + b^2) ~= 4.5
-----

29.9

I’m glad I’m not the only one. I may mention it to his teacher...if there’s any more school this year.