Question

Write the following proportion using colons. 7 is to 21 as 3 is to 9.

a. 7:21 = 3:9
b. 7:3 = 21:9
c. 21:7 = 3:9
d. 7:21 = 9:3

Answer 1

The answer is 7:21 = 3:9.

Answer 2

Option A.

Explanation:

There are two fraction given in this question and we have to write the proportion using colon.

Visually fractions
`(7)/(21)` and
`(3)/(9)` are different but when we simplify these fractions we get the actual relation between them.

We simplify
`(7)/(21)` first.

By dividing from 7 in the numerator and denominator we get

`((7)/(7))/((21)/(7))=(1)/(3)`

similarly we simplify the fraction
`(3)/(9)`

By dividing numerator and denominator by 3

`((3)/(3) )/((9)/(3) )=(1)/(3)`

Now we can say that both the fractions are equal.

`(7)/(21)=(3)/(9)=(1)/(3)`

So the ratio will be 7 : 21 = 3 : 9

Option A. will be the answer.