Every train carriage has 4 doors how many doors will the train have if there are 7 carriages

Answer: 28

Step-by-step explanation:

4*7=28

First write down the unit ratio that is involved.

In this case, it's train carriage/doors.

Next, we set up our proportion.

We know that for every train carriage, there are 4 doors.

So we have 1/4.

We are asked how many doors will there be is there are 7 carriages.

So we have 7/x.

The 7 must go on the top because our unit ratio says

that we must put train carriage/doors.

So we have 1/4 = 7/x.

Solving from here, we use the means-extremes property.

This states that the product of the extremes, (1) (x),

equals the product of the means, (4) (7).

So we have 1x = 28 or just x = 28.

This means that for 7 carriages, there are 28 doors.