TABLE 2-13 Given Below Is the Stem-And-Leaf Display Representing the Amount of Amount

TABLE 2-13
Given below is the stem-and-leaf display representing the amount of detergent used in gallons (with leaves in tenths of gallons) in a day by 25 drive-through car wash operations in Phoenix.
9 | 1 4 7
10 | 0 2 2 3 8
11 | 1 3 5 5 6 6 7 7 7
12 | 2 2 3 4 8 9
13 | 0 2
-Referring to Table 2-13, if a frequency distribution for the amount of detergent used is constructed, using "9.0 but less than 10.0 gallons" as the first class, the frequency of the "11.0 but less than 12.0 gallons" class would be ________.