Videocassette Recorder (VCR) Tapes Are Designed So That Users Can

question 32

Essay

Videocassette recorder (VCR) tapes are designed so that users can repeatedly record new material over old material. However, after a number of re-recordings the tape begins to deteriorate. A VCR tape manufacturer is experimenting with a new technology, which hopefully will produce longer-lasting tapes. Thirty of the old-style tapes and 30 utilising the new technology were used in an experiment. The tapes were used to record and re-record programs until they began to deteriorate. The number of re-recordings is assumed to be normally distributed. It is generally accepted that the number of re-recordings should exceed 55. Any tapes that do not meet this criterion are considered to be unacceptable. The number of re-recordings were observed and shown in the accompanying table. $$\begin{array} { | c | c | c | c | c | c | } \hline { \text { Old-style tapes } } &&& { \text { New-technology tapes } } \\\hline 60 & 61 & 48 & 68 & 70 & 58 \\\hline 51 & 46 & 66 & 74 & 72 & 69 \\\hline 66 & 63 & 61 & 77 & 73 & 49 \\\hline 73 & 55 & 71 & 59 & 66 & 61 \\\hline 71 & 49 & 76 & 52 & 58 & 59 \\\hline 47 & 56 & 55 & 66 & 51 & 49 \\\hline 60 & 62 & 64 & 62 & 59 & 57 \\\hline 52 & 51 & 63 & 51 & 56 & 66 \\\hline 64 & 68 & 52 & 50 & 55 & 76 \\\hline 47 & 55 & 58 & 63 & 68 & 78 \\\hline\end{array}$$ a. Do the data allow us to infer at the 10% significance level that the proportion of unacceptable new tapes is less than 20%?
b. Can we infer at the 10% significance level that the variance of the number of re-recordings of the new tape is less than 100?

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Definitions:

Price Elasticity Of Demand

A measure of how sensitive the quantity demanded of a good is to a change in its price.

Marginal Cost

The increase in total production cost that comes from making or producing one extra item.

Production Function

Refers to the relationship between input resources (like labor, land, and capital) and the output produced by these resources.

Marginal Product Of Labor

The additional output a firm gains from employing one more unit of labor, holding all other inputs constant.