Chuong and Hassan both drive 40km from home to work each day. One day, Chuong said to Hassan " If you drive at your usual speed, I will average 40kmph faster than you and arrive home in 20 minutes less time". Find Hassan's speed.
2 answers
do rtd make the distances equal to each other and the speed is 60km well that's what i got but im not very good at these lol
Hassan's time = 40/x hours
Chongs time = 40/(x+40) hours
their difference in time is 20 minutes or 1/3 hour
so
40/x - 40/(x+40) = 1/3
multiply each term by 3x(x+40) and simplify to get
x^2 + 40x - 4800 = 0
I used the quadratic formula to get
x = 52.11 mph
check:
Hassan's time = 40/52.11 = .7676 hours
Chong's time = 40/92.11 = .4343 hours
difference in time = .7676-.4343 = .3333 hours = 1/3 hour = 20 minutes
Chongs time = 40/(x+40) hours
their difference in time is 20 minutes or 1/3 hour
so
40/x - 40/(x+40) = 1/3
multiply each term by 3x(x+40) and simplify to get
x^2 + 40x - 4800 = 0
I used the quadratic formula to get
x = 52.11 mph
check:
Hassan's time = 40/52.11 = .7676 hours
Chong's time = 40/92.11 = .4343 hours
difference in time = .7676-.4343 = .3333 hours = 1/3 hour = 20 minutes
1 answer