Question

"A car starts at mile marker 21, and passes mile marker 33 after 20" minutes. It passes mile marker 38 after 23 minutes, and mile marker 42 after 27 minutes. What is the best estimate of the cars speed in miles per hour when it passes mile marker 40?

Answer 1

`speed= 60\,miles.hr^(-1)`

Step-by-step explanation:

According to the given:

The car passes 40 mile marker after 23rd minute and before 27th minute during which it passes mile marker 38 and mile marker 42 just after 27th minute.

∴time taken during this span,
`t=4min=(4)/(6) hr`

distance covered,
`d=4\,miles`

So, the estimated speed at the instant when the car passes 40 mile marker:

`speed=(distance)/(time)`

`speed=(4)/(((1)/(15) ))`

`speed= 60\,miles.hr^(-1)`