The dotplot shows heights of college​ women; the mean is 64 inches​ (5 feet 4​ inches) and the standard deviation is 3 inches. Complete parts a and b below.
Height (inches) and Standard Units
55
58
61
64
67
70
73



A dotplot titled "Height (inches) and Standard Units" with horizontal number line labeled from 55 to 73 in intervals of 3 contains dots of width 0.5 that are centered on number line values. Below each of the number line labels, a second label appears as follows: 55, negative 3; 58, negative 2; 61, negative 1; 64, 0; 67, 1; 70, 2; 73, 3. In general, from left to right the number of dots plotted for each value increases at an increasing and then decreasing rate from number line value 55 to 64 and decreases at an increasing and then decreasing rate from number line value 64 to 73. The number of dots plotted above each number line label is as follows: 55, 2; 58, 1; 61, 8; 64, 17; 67, 11; 70, 2; 73, 0.
Question content area bottom
Part 1
a. What is the​ z-score for a height of inches ​( feet ​)?