The data below were obtained from a detailed record of purchases of toothpaste over several years (courtesy of A. Banerjee). The usage times (in weeks) per ounce of toothpaste for a household taken from a consumer panel were

.74 .45 .80 .95 .84 .82 .78 .82 .89 .75 .76 .81

.85 .75 .89 .76 .89 .99 .71 .77 .55 .85 .77 .87

(a) Plot a dot diagram of the data.

(b) Find the relative frequency of the usage times that do not exceed .80.

(c) Calculate the mean and the standard deviation.

(d) Calculate the median and the quartiles.