Math 141, Sem. I, 1998-99 (R.A. Brualdi)
Handout 7 (September 28, 1998)
Topic: More Rate Problems


1. Page 54 of textbook: Numbers 3,4,5,6,7.
  
2.  Page 61 of textbook: Numbers 4,5,6,8.

3. An unfriendly starship has just emerged from behind the moon, 24,000
miles away from Earth, heading toward Earth at 8,000 miles per hour.
Earthlings are going to launch a missile which will fly at 1,000 miles
an hour to intercept the warship, but it will take 90 minutes of
preparation until the missile can be launched. How far from Earth will
the interception take place?

4. Let us continue on far into the future in which one of your
descendants has accumulated a college debt of $1,200,000. He is paying
off the debt at a rate of $100,000 a year. After 15 months, he gets a
salary increase which allows him to use an additional $14,000 a month
to pay off his debt. When will the debt be fully paid?

5. Your regular jogging path goes around a small lake, a distance of
1.4 miles. One morning, immediately after starting at your usual
jogging rate, you are passed by a rollerblader who is going twice as
fast as you are. Twelve minutes later the rollerblader passes you
again, having completed a circuit of the lake and caught up with you. 
How fast are you jogging?