It's not uncommon for hearing aids to malfunction and cancel the desired signal. IEEE Transactions on Speech and Audio Processing (May 1995) reported on a new audio processing system designed to limit the amount of signal cancellation that may occur. The system utilizes a mathematical equation that involves a variable, called a sufficient norm constraint. A histogram for realizations of I! produced using simulation, is shown on page 49.

a. Estimale the percentage of realizations of V with values ranging from .425 to .675.

b. Cancellation of the desired signal is limited by selecting a norm constraint I.: Find the value of V for a company that wants to market the new hearing aid so that only 10% of the realizations have values below the selected level.

2-38 Platelet-activating factor (PAF) is a potent chemical that occurs in patients suffering from shock, inflammation, hypotension. and allergic responses as well as respiratory and cardiovascular disorders. Consequently, drugs that effectively inhibit PAF, keeping it from binding to human cells, may be successful in treating these disorders. A bioassay was undertaken to investigate the potential of 17 traditional Chinese herbal drugs in PAF inhibition (H. Guiqui, Progress in Natural Science, June 1995). The prevention of the PAF binding process, measured as a percentage, for each drug is provided in the accompanying table.
75 DRUGP*E.D*T .......................................................... Drug PAF Inhibition (%)
Hai-feng-teng (Fuji)
Hai-feng-teng (Japan)
Shan-ju Zhang-yiz-hu-jiao Shi-nan-teng Huang-hua-hu-jiao Hua-nan-hu-jiao Xiao-yie-pa-ai-xiang Mao-ju Jia-,ju Xie-yie-ju Da-yie-ju Bian-yie-hu-jiao Bi-bo Duo-mai-hu-jiao Yan-sen Jiao-guo-hu-jiao Confidence Leve1(95.000%)
Source: Guiqui, H. "PAF receptor antagonistic principles from Chinese traditional drugs." Progress in Natural Science, Vol. 5, No. 3, June 1995, p. 301 (Table 1).
1.639542488

a. Construct a stem-and-leaf display for the data.

b. Compute the median inhibition percentage for the 17 herbal drugs. Interpret the result.

c. Compute the mean inhibition percentage for the 17 herbal drugs. Interpret the result.

d. Compute the mode of the 17 inhibition percentages.
Interpret the result.

e. Locate the median, mean, and mode on the stemand-leaf display, part

a. Do these measures of central tendency appear to locate the center of the data?