Students Per Computer
In the early years of microcomputers, school districts could not afford to buy a computer for every student. As the price of computers decreased, more and more school districts have been able to attainthis goal. The following table lists numbers of students per computer during these early years.
| Year | 1983 | 1985 | 1987 | 1989 |
| Students/Computer | 125 | 50 | 32 | 22 |
| Year | 1991 | 1993 | 1995 | 1997 |
| Students/Computer | 18 | 14 | 10 | 6 |
(a) Make a scatterplot of the data. Would a straight line model the data accurately? Explain.
(b) Discuss how well the formula
S = 
, y ≥ 1983
models these data, where S represents the students per computer and y represents the year.
(c) In what year dose the formula reveal that there were about 17 students per computer?
Solution
Form the above graph we can see that we can’t join all points with straight line, so we can’t use any straight line model.
B.
when y = 1983
S = 
Plug in y = 1983 in the given formula
S = 
S = 125
When y = 1985
S = 
S = 
S = 
S = 
S = 52
When y = 1987
S = 
S = 
S = 
S = 
S = 33
When y = 1989
S = 
S = 
S = 
S = 
S = 24
When y = 1991
S = 
S = 
S = 
S = 
S = 19
When y = 1991
S = 
S = 
S = 
S = 
S = 16
All calculated data’s are not same as the given table so we can say that given formula is not accurate for the given data.
C.
17 students per computer
Given value is S = 17, now plus in this value in the given formula
17 =
17(1 + 0.7 (y – 1983)) = 125
17(1 + 0.7y -1388.1) =125
17(0.7y – 1387.1) =125
11.9y -23580.7 = 125
11.9y = 125 + 23580.7
11.9y = 23705.7
Y = 
Y = 1992
So in the year of 1992 there are 17 students per computer.