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4th Edition

James Stewart

Publisher: Cengage Learning

ISBN: 9781337687805

Chapter 1.1, Problem 21E

a.

To determine

**To graph**: The number N

t | 1996 | 1998 | 2000 | 2002 | 2004 | 2006 |

N | 44 | 69 | 109 | 141 | 182 | 233 |

Expert Solution

**Given information**:

The number N

t | 1996 | 1998 | 2000 | 2002 | 2004 | 2006 |

N | 44 | 69 | 109 | 141 | 182 | 233 |

**Graph**:

The graph of N vs t can be drawn by using t as x-axis and N as y-axis. The obtained graphs is as like this,

**Interpretation**:

The obtained graph shows that the number of US cellular phone subscribers are continuously increasing from 1996 to 2006.

b.

To determine

**To calculate: **The estimation of the number of cell-phone subscribers at midyear in 2001 and 2005, Using the given graph.

Expert Solution

The estimated numbers of cell-phone subscribers at the midyear 2001 are __125 millions __and at the midyear 2005 are __207.5 millions__.

**Given information:**

The number N

t | 1996 | 1998 | 2000 | 2002 | 2004 | 2006 |

N | 44 | 69 | 109 | 141 | 182 | 233 |

**Calculation:**

Consider the given graph, the year 2001 lies in between 2000 and 2002 on the x-axis. Now, take the corresponding value of y with respect to x as 2001, it is find out to be 125 on this graph.

Similarly, the year 2005 lies in between 2004 and 2006 on the x-axis. Now, take the corresponding value of y with respect to x as 2005, it is find out to be 207.5 on this graph.

Therefore, the estimated numbers of cell-phone subscribers at the midyear 2001 are 125 millions and at the midyear 2005 are 207.5 millions.