Posted by **jim** on Monday, August 16, 2010 at 10:18pm.

Rachel allows herself 1 hour to reach a sale appointment 50 mile s away. After she has driven 30 miles, she realizes that she must increase her speed by 15 miles per hour in order to get there on time. What was her speed for the first 30 miles?

- algebra -
**drwls**, Monday, August 16, 2010 at 10:31pm
Call the initial speed V (in miles/h) and the time driving at that speed be t (in hours).

V*t + (V+15)*(1-t) = 50

V*t = 30

30 + (V+15)(1 - 30/V) = 50

(V+15)(1 - 30/V) = 20

V + 15 -30 -450/V = 20

V - 450/V = 35

V^2 -35V -450 = 0

(V-45)(V+10) = 0

Only the positive root, V = 45 mph, makes sense. Rachel finishes the trip at 60 mph

## Answer This Question

## Related Questions

- algebra - rachel allows herself one hour to reach a sales appointment 50 miles ...
- college algebra word problem - rachel allows herself 1 hour to reach a sales ...
- math....please help! - rachel allows herself 1 hour to reach a sales appt 50 ...
- algebra word problem: still stuck - question: rachel allows herself 1 hour to ...
- Trigonometry- Help! - After one hour in flight, an airplane is located 200 miles...
- algebra - A student runs 100 meters in 11 seconds. What is the speed of the ...
- maths - A motorist travels 120 miles to his destionation at an average speed of ...
- Math - A small truck is to be driven 300 miles on a freeway at a constant speed ...
- Calculus/ Optimization - A truck driver, on assignment from the owner of the ...
- Math/ Calculus Please HELP!!! - A truck driver, on assignment from the owner of ...

More Related Questions