Question

ms.lieber takes 4 hours to drive 210 miles from her home to yosemite National Park . if Miss Lieber's average speed for the first two hours is 60 miles per hour, find her average speed for the last 2 hours

Answer 1

This is correlation between distance-time-speed that we will use in answering
d = vt
t = d/v
v = d/t
d stands for distance, v stands for velocity/speed, t stands for time

First, we should count the distance she took for the first two hours
d = vt
d = (60)(2)
d = 120
For the first two hours, she took 120 miles

Second, calculate the distance for the next two hours
d = total distance - first distance
d = 210 - 120
d = 90
The remaining distance is 90 miles

Third, calculate the speed for the next 2 hours
s = d/t
s = 90/2
s = 45
The speed for the last two hours is 45 miles per hour

Answer: 45 miles/hour

Answer 2

60 x 2 = 120 miles for the 2 hours,
210 - 120 = 90
AVG speed for the last 2 hours is 45 MPH