Question

Zalmon walks 3/4 of a mile in 3/10 of an hour. What is his speed in miles per hour? А 2.3 miles per hour B 0.225 miles per hour C 2.6 miles per hourD 2.5 miles per hour

Answer 1

To solve the exercise you can use a rule of three, like this

`\begin{gathered} (3)/(4)\text{mi}\rightarrow(3)/(10)\text{hour} \\ x\text{ mi}\rightarrow1\text{ hour} \end{gathered}`
`\begin{gathered} x=\frac{1\text{ hour}\cdot(3)/(4)\text{ mi}}{(3)/(10)\text{ hour}} \\ x=\frac{1\cdot(3)/(4)\text{ mi}}{(3)/(10)} \\ x=(1\cdot(3)/(4))/((3)/(10))\text{ mi} \\ x=((3)/(4))/((3)/(10))\text{ mi} \end{gathered}`

To divide fractions you operate like this

`((a)/(b))/((c)/(d))=(a\cdot d)/(b\cdot c)`

Then, you have

`\begin{gathered} x=((3)/(4))/((3)/(10))\text{ mi} \\ x=(3\cdot10)/(4\cdot3)\text{ mi} \\ x=(10)/(4)\text{ mi} \\ x=(5)/(2)\text{ mi} \\ x=2.5\text{ mi} \end{gathered}`

Therefore, Zalmon's speed is 2.5 miles per hour.