Win a copy of Programming with Types this week in the Angular and TypeScript forum
or The Design of Web APIs in the Web Services forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Liutauras Vilda
  • Bear Bibeault
  • Paul Clapham
  • Jeanne Boyarsky
Sheriffs:
  • Junilu Lacar
  • Knute Snortum
  • Henry Wong
Saloon Keepers:
  • Ron McLeod
  • Tim Moores
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
Bartenders:
  • Frits Walraven
  • Joe Ess
  • salvin francis

puzzle of the day

 
Ranch Hand
Posts: 234
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
one side of the bottom layer of a triangular pyramid has 12 balls. How many are there in the whole pyramid?
 
Ranch Hand
Posts: 2545
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Originally posted by sona nagee:
one side of the bottom layer of a triangular pyramid has 12 balls. How many are there in the whole pyramid?


I will try my best:
The top layer side length is 1 ball, layer sum is 1 ball;
The second layer side length is 2, layer sum is 3;
..................
So: sum = 1 + 2 + ... + side length = 1/2 * ( length + 1) * length;
................
So the twelveth layer has 78 ;
So the grand total is:
1 + 3 + 6 + 10 + 15 + 21 + 28 + 36 + 45 + 55 + 66 + 78 = 364 !
 
sona gold
Ranch Hand
Posts: 234
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
great Don.....
wait for a new one .. every day
 
Ranch Hand
Posts: 210
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hey! Don Liu, how come you have a 3D mind like that! Tell me pls, how long I got to wait for May and Susan?
 
John Lee
Ranch Hand
Posts: 2545
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Something tells me...
 
Johnson Chong
Ranch Hand
Posts: 210
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Don Liu
Calculus of probabilities???!!!
What is that?
I've heard of calculus and probabilities but I just don't think I'll be able to find calculus of probabilities as a mathematical topic.
But I must say what a word.
 
Wanderer
Posts: 18671
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
One of the definitions of calculus is "A system or method of calculation". So "calculus of probabilities" just means "calculation of probabilities". As it happens though, serious probability theory has lots of integrals in it, so you definitely need a good grasp of [integral] calculus to understand it.
 
No, tomorrow we rule the world! With this tiny ad:
Java file APIs (DOC, XLS, PDF, and many more)
https://products.aspose.com/total/java
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!