Question

A small airplane flies 1200 miles with an average speed of 300 miles per hour. 2 hours after the plane leaves, a Boeing 747 leaves from the same point. Both planes arrive at the same time.what was the average speed of the boeing 747?

Answer 1

The small plane has the following parameters

Distance = 1200 miles

Speed = 300miles/hour

time = ?

`\begin{gathered} \text{Speed =}(dis\tan ce)/(time) \\ time\text{= }(1200)/(300) \\ \text{time = 4 hours} \end{gathered}`

If a Boeing 747 leaves 2 hours later, the total time becomes 4hours + 2 hours = 6 hours

Considering the distance of the small plane after 6 hours, we have

`\begin{gathered} \text{distance = sp}eed*\text{ time} \\ d\text{ = 300 }*6 \\ d\text{ =1800 miles} \end{gathered}`

So the total distance = 1800 miles

Hence the speed of the Boeing 747 will be

`\begin{gathered} \text{Speed =}(dis\tan ce)/(time) \\ \text{distance = 1800 miles } \\ time\text{ = 2hours} \end{gathered}`
`\begin{gathered} \text{speed = }(1800)/(2) \\ \text{speed = 900 miles/hour} \end{gathered}`

The average speed of the Boeing 747 is 900 miles/ hour