People suffering from Alzheimer’s disease often have dif fi culty performing basic activities of daily living

(ADLs). In one study (“Functional Status and Clinical Findings in Patients with Alzheimer’s Disease,” Journal of Gerontology [1992]: 177– 182), investigators focused on six such activities: dressing, bathing, transferring, toileting, walking, and eating. Here are data on the number of ADL impairments for each of 240 patients:

Number of impairments 0 1 2 3 4 5 6 Frequency 100 43 36 17 24 9 11

a. Determine the relative frequencies that correspond to the given frequencies.

b. What proportion of these patients had at most two impairments?

c. Use the result of Part

(b) to determine what proportion of patients had more than two impairments.

d. What proportion of the patients had at least four impairments?