Internet cost

This task is about comparing different prices for internet access.
Three companies offer different plans to access the Internet. Here are their monthly charges.

  • SHARP charge $1.50 per hour.
  • REAL charge a $10.00 fee for up to 15 hours use and $2.00 per hour after that.
  • WINS charge $2.00 per hour for the first 10 hours and $1.00 per hour after that.
 
a)
 
What would it cost you if you used 20 hours of access time one month and used the scheme offered by
 
i)     SHARP?   $___________
 
ii)    REAL?      $___________
 
iii)   WINS?      $___________

 
b)
 
This graph shows the cost of Internet use with the company REAL for different levels of monthly usage. On this graph draw the lines showing the Internet costs using the other two companies.
 
c)
Which company would be cheapest if your average monthly Internet use was
 
i)     10 hours? __________
 
ii)     less than 5 hours? __________