Rational Equations

Question

Need help with these problems, having some issues with them!

 

In 2 minutes, a conveyor belt moves 200 pounds of recyclable aluminum from the delivery truck to a storage area. A smaller belt moves the same quantity of cans the same distance in 4 minutes. If both belts are used, find how long it takes to move the cans to the storage area.

 

A plane flies 440 miles with the wind and 340 miles against the wind in the same length of time. If the speed of the wind is 25 mph, find the speed of the plane in still air?

 

Smith Engineering is in the process of reviewing the salaries of their surveyors. During this review, the company found that an experienced surveyor can survey a roadbed in 3 hours. An apprentice surveyor needs 5 hours to survey the same stretch of road. If the two work together, find how long it takes them to complete the job.

 

Two joggers, one averaging 7 mph and one averaging 5 mph, start from a designated initial point. The slower jogger arrives at the end of the run 20 minutes after the other jogger. Find the distance of the run.

Answer 1

R-

Well, I'm not going to do all your homework!  But I will do one and that should give you a clue.  Let's look at Smith Engineering.  

One guy does a whole job in 3 hours, so in 1 hour he does 1/3 of the job.  The slower guy takes 5 hours, so in 1 hour he does 1/5 of the job.  Let x = time it take them together.

x (1/3) + x (1/5) = 1   

x/3 + x/ 5 = 1     Clear fractions by multiplying by sides by 15

5x + 3x = 15

8x = 15

x = 15/8 = 1 7/8 hr.

 

Try to do the others.  Show us your work and we can help you find your error.

 

Mary