SOLUTION: A bus travelled 150 miles at a certain speed. If the bus went 10 miles faster, travel time will be decreased by 30 minutes. What is the speed of the bus?

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Question 352564: A bus travelled 150 miles at a certain speed. If the bus went 10 miles faster, travel time will be decreased by 30 minutes. What is the speed of the bus?
Found 2 solutions by mananth, josmiceli:
Answer by mananth(16949) (Show Source):
You can put this solution on YOUR website!
let speed of bus be x mph
if it travels 10 mph faster then its speed = x+10 mph.
distance = 150 miles.
time taken with original speed - time taken with increased speed = 1/2 hour
...
time = distance /speed
150/x - 150/(x+10)= 1/2
LCM = x(x+10)
150(x+10)-150x/x(x+10) = 1/2
150x+1500 -150x = x(x+10) / 2
1500 *2 = x^2 +10x
x^2+10x-3000 =0
x^2+60x-50x-3000=0
x(x+60)-50(x+60)=0
(x+60)(x-50)=0
x=50 mph the original speed.
,,,
m.ananth@hotmail.ca

Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
given:
mi

Use quadratic formula:

The negative square root cannot be a valid speed, so
The speed of the bus is 50 mi/hr
check answer:

hrs
and, since

OK