Problema Solution
Kathy took a helicopter ride to the top of a mountain glacier. The flight covered a distance of 120 kilometers. Kathy stayed on top of the glacier for 1/2 hour. She then flew to a town, 260 kilometers away. The helicopter averaged 20 kilometers per hour faster going to the town than one flight up to the top of the glacier. the total time involved in the outing was 2 hours. Find the average speed of the helicopter going to the glacier.
Answer provided by our tutors
Let
v = the average rate of the helicopter to the top of the glacier, v>0
v + 20 = the average rate of the helicopter back to the town
d1 = 120 km
t1 = 1/2 hr
d2 = 260 km
t2 = 2 hr
Since speed = distance/time follows time = distance/speed.
Now we can write:
d1/v + t1 + d2/(v + 20) = t2
120/v + 1/2 + 260/(v + 20) = 2
........
click here to see the equation solved for v
........
v = 240 km/h
We ignore the negative root since we assumed that the rate is positive (v>0).
The average speed of the helicopter going to the glacier was 240 kilometers per hour.