They are a method for showing the frequency of a data plot in a much more compact and numerical way.
1[2 3
2[1 7
3[3 4 5 7
4[ 0 0 1
Key 1[2= 12
meaning that 3[5 is 35 and 4[0 is 40 and so and so forth
3/64 inches
explaination: math
W=3L
W+W+L+L=72
Replace W with 3L: 3L+3L+L+L=72
8L=72
L=9
W=27
The first question is “32.4”
I’ll come back if I find the other