Asked by Donald
a woman drove a distance of 240km on the return journey she drove 20km/h faster and took two hnurs less. what was her speed on the outward journey?
Answers
Answered by
Reiny
speed on first trip --- x km/h
speed on return trip -- x+2 km/h
recall that time = distance/rate
difference in their times = 2 hrs
----> 240/x - 240/(x+20) = 2
everybody times x(x+20)
240(x+20) - 240x = 2x(x+20)
240x + 4800 - 240x = 2x^2 + 40x
x^2 + 20x - 2400 = 0
(x-40)(x + 60) = 0
x = 40 or x is a negative speed -->reject
She went 40 km/h on her outward trip
and 60 km/h on her way back.
speed on return trip -- x+2 km/h
recall that time = distance/rate
difference in their times = 2 hrs
----> 240/x - 240/(x+20) = 2
everybody times x(x+20)
240(x+20) - 240x = 2x(x+20)
240x + 4800 - 240x = 2x^2 + 40x
x^2 + 20x - 2400 = 0
(x-40)(x + 60) = 0
x = 40 or x is a negative speed -->reject
She went 40 km/h on her outward trip
and 60 km/h on her way back.
Answered by
Fortunate
Good
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