Respuesta :
Answer:
So her average speed for the entire trip is 30 mph (miles per hour).
Step-by-step explanation:
Use distance = rate x time
18 minutes is 3/10 of an hour.
So the distance to the store is:
d = 20*(3/10) = 6 miles
The distance downhill is the same, 6 miles. So:
6 = (60)t
6/60 = t
1/10 = t
Where t is the time it took to go back home. So t is .1 hour (6 minutes).
To calculate average speed we use the formula:
average speed = total distance/ total time
average speed = (6+6)/(.3 + .1) = 12/(.4) = 30
So her average speed for the entire trip is 30 mph (miles per hour).
Answer:
Step-by-step explanation:
let normal speed=x
speed uphill=x-y
speed downhill=x+y
x-y=20
x+y=60
2x=80
x=40
speed uphill=20 mph
time=18 minutes=\frac{18}{60}=\frac{3}{10} hrs
distance=speed ×time=20×\frac{3}{10}=6 miles
downhill speed=60 mph
time taken=\frac{6}{60}=\frac{1}{10} hr
total time =\frac{3}{10}+\frac{1}{10}=\frac{3+1}{10}=\frac{4}{10}
total distance=6+6=12 mile
average speed=12÷\frac{4}{10}=12×\frac{10}{4}=30 mph
total time=
