Question

A brother and sister leave school at the same time, moving in opposite directions. If the brother walks away at a speed of 3.5 miles per hour, and the sister runs at a speed of 7.5 miles per hour, how far apart are they after half an hour?A 2.5 milesB 40 miles c 5.0 milesD 5.5 miles

Answer 1

D. 5.5 miles

Step-by-step explanation:

The time taken by both siblings = Half an hour = 0.5 hour

`\text{Distance covered=Speed}* Time`

The brother walks away at a speed of 3.5 miles per hour. The distance covered by the brother in half an hour:

`\begin{gathered} =3.5*0.5 \\ =1.75\text{ miles} \end{gathered}`

The sister runs at a speed of 7.5 miles per hour. The distance covered by the sister in half an hour:

`\begin{gathered} =7.5*0.5 \\ =3.75\text{ miles} \end{gathered}`

Since they are moving in opposite directions, the distance between them will be the sum of the distances in each direction.

`\begin{gathered} \text{Distance apart=1.75+3.75} \\ =5.5\text{ miles} \end{gathered}`

The siblings are 5.5 miles apart after half an hour.