Proportions

[KWF]

What does the following indicate? a is to b as c is to d.

Here is an example: 2:4 = 5:10

This is 2 is to 4 as 5 is to 10.

I thank you for your reply.

 

[Bob Brown MSEE]

What does the following indicate? a is to b as c is to d.

"a is to b as c is to d", indicates each of the 3 following expressions:

1) a:b= c:d
2) a/b=c/d
3) ad=bc

 

[KWF]

A reply for Denis:

Is this correct?

(1 divided by 2 equals 1/2 is to 2 divided by 2 equals 1) as (5 divided by 10 equals 1/2 is to 10 divided by 10 equals 1).

1/2 equals 1/2

 

[KWF]

A reply for Bob Brown MSEE:

The product of the means equals the product of the extremes.

20 = 20

 

[Bob Brown MSEE]

20 = 20

Right for#3

"a is to b as c is to d", indicates each of the 3 following expressions:

1) a:b= c:d
2) a/b=c/d
3) ad=bc

 

[Quaid]

What does the following indicate?

a is to b as c is to d.

It indicates a proportion.

 

[guitarguy]

This indicates that a is in the same proportion to b as c is in proportion to d.

In other words if a is half of b then c is half of d.

Or, if a is one third of b then c is one third of d.

The numbers could be anything as long as they are in the correct proportion: a=500 b=1000 c=4 d=8
satisfies the relationship: a:b=c:d. Because a is half of b and c is half of d.