John finished his Math home work in 30 minutes and Geography home work in one hour. Would it be right to say that ratio of the time spent on Math to the time spent on Geography is 30:1?
No, because this ratio tells that John spent 30 times more time on Math than on Geography, which is not true. This error occurred because of the comparison of unlike quantities like minutes and hours. Therefore, when you use a ratio to compare two quantities, write both the quantities in the same units.
In the above example, converting the time spent on Geography into minutes we get 60 minutes. Therefore, the ratio of time spent on the two subjects = 30:60 = 1:2. This is correct because the time spent on Geography is actually double the time spent on Math.
Directions: Find the ratio of the first quantity to the second. Also write at least ten examples of your own.