a cyclist travels at a rate of 20 km/hr for 30 minutes. the rider takes a half-hour lunch break and then proceeds to travel 30 km in the next 60 minutes. what i

Question

a cyclist travels at a rate of 20 km/hr for 30 minutes. the rider takes a half-hour lunch break and then proceeds to travel 30 km in the next 60 minutes. what is the bicyclist's average speed over the entire trip?

 

for science

Answer 1

distance=rate*time

d=20*(1/2) (30 minutes=1/2 hour)

d=10 km traveled

 

d=rt

30=r*1 (60 minutes=1 hour)

30=r

r=30 km per hour

 

total distance=rate*total time

total distance=10 km+30 km=40 km

total time=(1/2) hour+1 hour=1 1/2 hours or 1.5 hours

40=rate*1.5

rate=40/1.5

rate=400/15

rate=80/3 (you don't have to simplify if you don't want to)

rate=26.666... km per hour or 26 2/3 km per hour for the average speed

Answer 2

The average speed is the total distance divided by the total time.

 

So he went 20 km/hr for 30 minutes, which is 1/2 hour, so in that time he traveled 20 * 1/2 km = 10 km

 

During lunch he didn't travel at all.

 

Then he went 30 km in the next 60 minutes.  So he traveled a total of 40 km (10 + 30).

 

The total time was 30 + 30 + 60 = 2 hours.

 

So his average speed was 40 km / 2 hours, or 20 km/hr.