Garlic has long been considered a remedy to ward off the common cold. A British researcher organized an experiment to see if this generally held belief is true. A random sample of 146 volunteers was recruited. Half the sample took one capsule of an alli-cin-containing garlic supplement each day. The others took a placebo. The results for each volunteer after the winter months were recorded in the following way.

Column

1. Identification number

2. 1 = allicin-containing capsule; 2 = placebo

3. Suffered a cold (1 = no, 2 = yes)

4. If individual caught a cold, the number of days until recovery (999 was recorded if no cold)

a. Can the researcher conclude that garlic does help prevent colds?

b. Does garlic reduce the number of days until recovery if a cold was caught?