MHB Q&A: Understanding Part C of a Round Trip Problem

  • Thread starter Thread starter find_the_fun
  • Start date Start date
Click For Summary
The discussion centers on the confusion regarding the calculation of return routes in part c of a round trip problem. The answer key indicates there are 14 ways to reach point C, but the user believes the return options vary based on the road taken. They argue that if certain roads are used to reach C, it limits the return routes differently depending on which roads are restricted. The user concludes that if R1R5 is used to get to C, the only restricted return trip is R5R1, allowing for other routes back. The core issue is the misunderstanding of how the restrictions on return trips affect the total number of valid routes.
find_the_fun
Messages
147
Reaction score
0
I don't understand the answer for part c of the following question

View attachment 1615

The answer key gives 14x13 as the solution to part c. I understand there are 14 ways to get to point C but depending on which road can no longer be used, there is anywhere between 10 and 13 ways to return home. For example, say R8 was taken to get to C. Then there are 14-1 ways to make the return trip (just don't use R8). However, if R1R5 is used then we can't use either R1 (so now there are 3x3+2=11 ways to make the trip) or R5 (so now there are 2x4+2=10 ways to make the trip). What is wrong with my reasoning?
 

Attachments

  • question.png
    question.png
    50.9 KB · Views: 84
Physics news on Phys.org
As I understand the problem statement in c), if Linda takes R1R5 to get from A to C, there is a single trip she is not allowed to take back: R5R1. All other trips are allowed.
 

Thread 'Please Explain (actually explain) The Monty Hall Problem'

Hello, I'm joining this forum to ask two questions which have nagged me for some time. They both are presumed obvious, yet don't make sense to me. Nobody will explain their positions, which is...uh...aka science. I also have a thread for the other question. But this one involves probability, known as the Monty Hall Problem. Please see any number of YouTube videos on this for an explanation, I'll leave it to them to explain it. I question the predicate of all those who answer this...
View full post »

Thread 'A variant of the Monty Hall problem'

There is a nice little variation of the problem. The host says, after you have chosen the door, that you can change your guess, but to sweeten the deal, he says you can choose the two other doors, if you wish. This proposition is a no brainer, however before you are quick enough to accept it, the host opens one of the two doors and it is empty. In this version you really want to change your pick, but at the same time ask yourself is the host impartial and does that change anything. The host...
View full post »

Thread 'Value of intuitionistic logic'

I'm taking a look at intuitionistic propositional logic (IPL). Basically it exclude Double Negation Elimination (DNE) from the set of axiom schemas replacing it with Ex falso quodlibet: ⊥ → p for any proposition p (including both atomic and composite propositions). In IPL, for instance, the Law of Excluded Middle (LEM) p ∨ ¬p is no longer a theorem. My question: aside from the logic formal perspective, is IPL supposed to model/address some specific "kind of world" ? Thanks.
View full post »

Similar threads

I Understanding Spacetime simultaneity in twin paradox scenarios
Replies
35
Views
3K
I A Sequence T based on the Rule of Three
Replies
15
Views
2K
Solve Thevenin Problem: A & B for R1 Circuit
Replies
1
Views
2K
Finding the Magnitude and Direction of the Displacement Vector for a Ship's Trip
Replies
2
Views
5K
I Einstein brother-in-law elevator
Replies
11
Views
2K
Counting problem - how many ways....
Replies
4
Views
3K
I One Way Twin Revisited: Understanding Tim & Tom's Watches on Home & Northbound
Replies
37
Views
3K
Solution of basic special relativity problem
Replies
4
Views
1K
Engineering Solve Delta-Wye Circuit: Find R3, R12 & R13
Replies
7
Views
4K
Auto/Motor Honda NT700V Deauville motorcycle maintenence: Drive shaft
Replies
27
Views
4K