Sunday

August 31, 2014

August 31, 2014

Posted by **monica** on Sunday, August 24, 2008 at 10:06am.

- math -
**Reiny**, Sunday, August 24, 2008 at 1:09pmlet the distance around the track be d km

so the time needed to qualify is 2d/100

his time for the first lap is d/75 hours

let his speed for the second lap be r km/h

so the time for his second lap is d/r hours

total time = d/75 + d/r = (dr+75d)/75

then (dr+75d)/75 = 2d/100

divide both sides by d

(r+75)/75 = 2/100

you finish it, let me know what you got

- math -
**monica**, Sunday, August 24, 2008 at 1:26pmi got 3675, but that doesn't make any sense, he has to go 3675 mph?

- math -
**drwls**, Sunday, August 24, 2008 at 5:18pmI believe Reiny meant to write

d/75 + d/r = (dr + 75 d)/(75 r)

=================================

d/75 + d/r = 2d/100

1/r = 2/100 - 1/75 = 6/300 - 4/300 = 1/150

r = 150

**Related Questions**

physics - to qualify for a race, a car must average 350 km/hr for four laps. If ...

physic - 1) if you live 10.0 km from your school and the bus takes 0.53 h to ...

physic - In order to qualify for the finals in an race, a runner must achieve an...

Physics - A runner completes an 850m race with two laps of the 425m track in the...

Math - Tom can complete 5 laps of a race track in 15 minutes. Mark can finish 10...

Biomechanics - John and Al are in a 15 km race. John averages 4.4 m/s during the...

Basic Biomechanics - John and Al are in a 15 km race. John averages 4.4 m/s ...

Math - Jim and joe are training for a big race by running a total of 60 laps ...

Science/Math - John and Al are in a 15 km race. John averages 4.4 m/s during the...

Science - If you drive 20 laps around a circular race track at 100 m/s what do ...