Project 73

With the simplifying assumption that that this data set represents approximately a simple random sample of all pennies in circulation in Tacoma, Washington in the summer of 2008, find a 95% confidence interval for the proportion of such pennies minted before 1982.

This data set consists of the years and masses of 100 randomly selected pennies
(from a piggy bank in Tacoma, Washington),
the masses being measured to the hundredth of a gram. The measurements were made
one evening during the summer of 2008 using a MyWeigh Durascale (50 g by 0.01 g
capacity).
The order of the pennies in the data set is the order in which their masses
were measured (which was randomly determined).
The two variables and their units are summarized in the following table.

The variables in the data set are as follows:

Name | Units | Description |

year | years | year in which the penny was minted |

mass | grams | mass of the penny |

The full data set in csv format is at: