Question

Martin can run 1 mile in 7 minutes. What proportions can be written from this information?

Answer 1

a and d

Explanation:

Answer 2

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

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

Explanation:

Verify each case

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

Multiply in cross and then compare both sides

`1*21=7*3`

`21=21` ----> is true

therefore

Is a valid proportion

case 2)
`(1)/(21)=(3)/(7)`

Multiply in cross and then compare both sides

`7*1=21*3`

`7=63` ----> is not true

therefore

Is not a valid proportion

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

Multiply in cross and then compare both sides

`21*7=1*3`

`147=3` ----> is not true

therefore

Is not a valid proportion

case 4)
`(7)/(1)=(21)/(3)`

Multiply in cross and then compare both sides

`3*7=1*21`

`21=21` ----> is true

therefore

Is a valid proportion

case 5)
`(1)/(7)=(21)/(3)`

Multiply in cross and then compare both sides

`3*1=7*21`

`3=147` ----> is not true

therefore

Is not a valid proportion