Question

A certain plant grows 1 3/4 inches every week. How long will it take the plant to grow 7 3/4 inches?

Answer 1

Firsr, we must convert the mixed fractions to simple fractions in order to solve this question:

`1\text{ }(3)/(4)=(4\cdot1+3)/(4)=(7)/(4)`

and

`7(3)/(4)=(4\cdot7+3)/(4)=(31)/(4)`

Now, we can solve this question by means of the rule of three:

`\begin{gathered} (7)/(4)\text{inches ------- 1 we}ek \\ (31)/(4)\text{inches ------- x} \end{gathered}`

hence,

`\begin{gathered} x=((31)/(4)\cdot1)/((7)/(4)) \\ x=((31)/(4))/((7)/(4)) \end{gathered}`

by applying the Sandwich law, we have

`\begin{gathered} x=(31\cdot4)/(7\cdot4) \\ x=(31)/(7) \end{gathered}`

In mixed fraction, 31/7 is

`4(3)/(7)`

that is, 4 and 3/7 weeks