Register to reply

Division for ratios

by Mr Davis 97
Tags: division, ratios
Share this thread:
Mr Davis 97
#1
Aug11-14, 11:35 AM
P: 9
Why is division used for ratios? For example, if we have 1 dog for every 2 cats, then why can this relation be modeled by the division? Since the ratio can essentially have the value of 1/2 or 2, then what is the significance of these two distinct numbers in relation to the ratio? How does the value of the fraction 1/2, which is 0.50, relate to the ratio 1 dog to 2 cats? If we said we had a 0.50 ratio of dogs to cats, what does that mean?
Phys.Org News Partner Mathematics news on Phys.org
Researcher figures out how sharks manage to act like math geniuses
Math journal puts Rauzy fractcal image on the cover
Heat distributions help researchers to understand curved space
Einj
#2
Aug11-14, 11:50 AM
P: 328
There are different reasons. First of all the ratio is a much easier number to understand, depending if it is greater or smaller than 1 (and how much grater/smaller it is) you can have an immediate idea of what's going on. If you are using small numbers (as in your example) it is clear that the ratio doesn't really add any information. However if the numbers you are dealing with are high it is much more complicated to evaluate the relationship between the two quantities just "by eye".

Moreover, the ratio gives you the percentage. For example, as you said, if I know that the ratio dogs/cats is 0.37 then this means that the number of dogs is the 37% of the number of cats.
MrAnchovy
#3
Aug11-14, 11:56 AM
P: 545
Quote Quote by Mr Davis 97 View Post
Why is division used for ratios?
Because it works.

Quote Quote by Mr Davis 97 View Post
For example, if we have 1 dog for every 2 cats, then why can this relation be modeled by the division?
Because 1 dog for every 2 cats is the same as ## \frac12 ## a dog for every 1 cat.

Quote Quote by Mr Davis 97 View Post
Since the ratio can essentially have the value of 1/2 or 2, then what is the significance of these two distinct numbers in relation to the ratio?
The significance of ## \frac12 ## is that we have ## \frac12 ## a dog for every 1 cat, and the siginficance of 2 is that we have 2 cats for every 1 dog.

Quote Quote by Mr Davis 97 View Post
If we said we had a 0.50 ratio of dogs to cats, what does that mean?
That we have 0.5 dogs for every cat (which is the same as 1 dog for every 2 cats, or 2 cats for every 1 dog etc...)

phinds
#4
Aug11-14, 11:57 AM
PF Gold
phinds's Avatar
P: 6,507
Division for ratios

Quote Quote by Mr Davis 97 View Post
Why is division used for ratios?
What would you prefer to use? Do you want everyone to spell it out in words every time?
HallsofIvy
#5
Aug11-14, 02:28 PM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,682
A "ratio" is defined as a fraction which is an implied division.


Register to reply

Related Discussions
Transition from lower division to upper division as a physics major Academic Guidance 0
Difficulty of lower division courses vs. upper division (undergraduate) Academic Guidance 10
Synthetic division or Long division of polynomials? General Math 6
GPA of Upper Division & Lower Division courses and M.S degree Academic Guidance 1
Division with variables (I think I'd call this double division) Precalculus Mathematics Homework 5