The answer is 20 not 5 or 15 or 10
The standard deviation of the frequency distribution is 5.54
<h3>How to determine standard deviation?</h3>
The table of values is given as:
x f(x)
0-3 13
4-7 13
8-11 10
12-15 11
16-19 0
20-23 3
Rewrite the table by calculating the class midpoints:
x f(x)
1.5 13
5.5 13
9.5 10
13.5 11
17.5 0
21.5 3
Start by calculating the mean using:

This gives

Evaluate

The standard deviation is then calculated as:

So, we have:

Evaluate

Solve

Hence, the standard deviation is 5.54
Read more about standard deviation at:
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Easy
just find the slope between those 2 points
f(-6)=6
f(-3)=0
slope=rise/run=-6/3=-2
slope is -2
A is answer
Answer:triangles 20 12 28 and15 9 21
Step-by-step explanation: