Speed problem

Question

Carla began her workout jogging for 3 miles then bicycling for 20 miles. She bicycled at a speed tht was 7 miles per hour faster than she jogged. She spent twice as much time bicycling as jogging. What was her jogging speed and what was her bicycling speed?

Answer 1

Let x = jogging speed and x + 7 = biking speed

 

time biking  = 2(time jogging)

 

Distance = (rate)(time), so time = distance/rate

 

 

20/(x + 7) = 2(3/x)

 

20/(x + 7) = 6/x

 

20x = 6(x + 7)

20x = 6x + 42

14x = 42

  x = 3

 

ANSWER:  jogging speed = 3 mph, biking speed  = 10 mph 

 

 

 

 

 

 

 

 

Answer 2

J = jogging speed

J + 7 = bicycling speed

 

20 / (J + 7) = time bicycling

3 / J = time jogging

 

20 / (J + 7) = (2) (3 / J)

20 / (J + 7) = 6 / J

20J = 6(J + 7)

20J = 6J + 42

14J = 42

J = 3

 

Her jogging speed was 3 mph and her bicycling speed was 10 mph.