6. An airplane flies 450 km from Raleigh to Washington DC at 500 km/hr. It stops for a while in Washington DC and then flies 370 km to New York at 500 km/hr. If the average speed for the entire trip from Raleigh to New York is 125 km/hr how long did the plane stop in Washington DC? A 6.56 hours B 4.92 hours C 1.64 hours D 1.46 hours E 2.62 hours Solution Time required to travel From Raleigh to New York, t1 = (450 / 500) + (370 / 500) t1 = 1.64 hr When average speed is 125 km/hr, t2 = (450 + 370) / 125 t2 = 6.56 hr Let, plane stops in washington DC for time t. t = t2 - t1 t = 6.56 - 1.64 t = 4.92 hours (option B) .

1. 6. An airplane flies 450 km from Raleigh to Washington DC at 500 km/hr. It stops for a while in
Washington DC and then flies 370 km to New York at 500 km/hr. If the average speed for the
entire trip from Raleigh to New York is 125 km/hr how long did the plane stop in Washington
DC? A 6.56 hours B 4.92 hours C 1.64 hours D 1.46 hours E 2.62 hours
Solution
Time required to travel From Raleigh to New York,
t1 = (450 / 500) + (370 / 500)
t1 = 1.64 hr
When average speed is 125 km/hr,
t2 = (450 + 370) / 125
t2 = 6.56 hr
Let, plane stops in washington DC for time t.
t = t2 - t1
t = 6.56 - 1.64
t = 4.92 hours (option B)