Homework Help: Math

Posted by Stella on Saturday, October 3, 2009 at 1:50am.

Hello, I have trouble doing this problem:
Sarah can bicycle a loop around the north part of Lake Washington in 2 hours and 40 minutes. If she could increase her average speed by 1km/hr, it would reduce her time around the loop by 6 minutes. How many kilometers long is the loop?

So this is what I attempted to do:
I change the 2hours 40 min to 160 mins
then i tried changing it to hours which was 2.6666667
and i tried to plug it in
d=r*t
but then i got confused..please help me =)

Math - drwls, Saturday, October 3, 2009 at 6:45am
Let L be the loop distance. Let V be her speed when it takes 2.6667 hours.

You have two unknowns and must combine two equations to get an answer.

At speed V + 1 , she takes 2 hours 34 minutes = 2.5667 hours
At speed V, she takes 2.6667 hours

D = V * 2.6667 = (V+1)* 2.5667
(V+1)/V = 2.6667/2.5667 = 1.03896
V + 1 = 1.03896 V
0.03896 V = 1
V = 25.67 km/h
D = 25.67 * 2.6667 = 68.4 km

Answer this Question

Related Questions

pre calc - The front sprocket off a bicycle is 12 centimeters and the rear one ...
pre calc - The front sprocket off a bicycle is 12 centimeters and the rear one ...
physics - A mass m = 76.0 kg slides on a frictionless track that has a drop, ...
Please Please Help-Physics - I am having trouble figuring out this question: ...
Quantiative Methods - Industrial Designs has been awarded a contract to design a...
physics - A mass m = 73 kg slides on a frictionless track that has a drop, ...
MATH - Rate Problem: Mr. Stewart rode a distance of 12miles out into the country...
physicssss - A mass m = 73 kg slides on a frictionless track that has a drop, ...
physics - what is the difference in the induced current in a wire loop when a ...
physics - A mass m = 76.0 kg slides on a frictionless track that has a drop, ...

For Further Reading

First Name:
School Subject:
Answer: