Instruction 2 -Referring to Instruction 2

Short Answer

Instruction 2.8
Given below is the stem-and-leaf display representing the amount of detergent used in litres (with leaves in 10ths of litres) in a month by 25 drive-through car wash operations in Auckland.
$$\begin{array} { | l | l | } \hline \text { Stem } & \text { Leaves } \\\hline 9 & 147 \\\hline 10 & 02238 \\\hline 11 & 135566777 \\\hline 12 & 223489 \\\hline 13 & 02 \\\hline\end{array}$$
-Referring to Instruction 2.8,if a frequency distribution for the amount of detergent used is constructed,using '9.0 but less than 9.9 litres' as the first class,the frequency of the '11.0 but less than 11.9 litres' class would be _________.