Question

Clifton drove for 3 hours at 52 mph. How fast must he drive during the next hour in order to have an average speed of 55 mph?

Answer 1

Answer:

64 mph

Step-by-step explanation:

Given that:

Speed for the first 3 hours = 52 mph

Average speed for 4 hours = 55 mph

To find:

Speed for the next hour = ?

Solution:

Formula for average speed is given as:

$Average\ Speed = \dfrac{Total\ Distance}{Total \ Time \ Taken}$

Formula for Distance:

$Distance =Speed \times Time$

Distance traveled in first 3 hours:

$Distance =52\times 3 = 156\ miles$

Let the speed for the next hour = u mph

Distance traveled in 1 hour = $u \times 1 = u\ miles$

Total distance traveled = (156 + u) miles

Total time = 4 hours

Average Speed = 55 mph

Putting the values in formula:

$55 = \dfrac{156+u}{4}\\\Rightarrow 220 = 156+u\\\Rightarrow \bold{u = 64\ mph }$

So, the answer is: 64 mph