:3c. In a Public Health Service Study of 1964, a histogram was
plotted showing the number of cigarettes per day smoked by each
subject (male, current smokers), as shown in diagram ? on page ?
of the test.  The density is marked in parentheses.  The class
intervals include the right endpoint, not the left. <p>

: <p>

a.  0.25 of 1%
 b.  0.50 of 1%
 c.     5%
 d.     10%
 e.     25% <p>

(There are twenty cigarettes in a pack.) <p>