Answer:
160 degrees
Step-by-step explanation:
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
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Answer:
-3
Step-by-step explanation:
It is B
4m + n = 10
- n -n
4m =10-n
------ -----
4 4
m =10-n
-----
4
The wall can be built in 22 days by 6 workers in first 6 days and 9 workers in the rest of time.
<h3>How to use inverse proportionality to determine building time of a wall</h3>
In this question we must use the definition of <em>inverse</em> proportionality, in which the number of workers (
), no unit, is inversely proportional to the <em>building</em> time (
), in days.
According to the statement, 6 workers spent 6 days building a wall and there are 24 days left for completion, but 3 more workers entered to reduce building time, which can be represented by the following expression:


In this scenario, the wall can be built in 22 days. 
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