Well, first off, let's find what is the slope of BC

now, a line perpendicular to that one, will have a negative reciprocal slope, thus

now, we know the slope "m" of AB is -2 then, thus
The correct option is 20.
The score found for the sample is 20.
<h3>What is Standard error?</h3>
A standard error is a statistic that is applied to test the distribution of data. This metric is comparable to standard deviation. We can calculate the standard error if we know the sample size & standard deviation. It assesses the mean's precision.
Now, according to the question;
Sample mean; 
Sample variance; 
Thus, 
Standard error SE = 1
The amount of scores with in sample must be determined here.
The standard error formula is as follows:

We might rearrange the formula as follows:

Substituting the values;

The sample's number of scores n = 19.98 = 20 (round up)
Therefore, the scores are in the sample is 20.
To know more about the Standard error, here
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Consider,

. Let's say

then the problem reduces to

. (Do you understand this step?)
So then replacing a again with our definition we get,

.
Answer:
x = (5/3 , 7)
Step-by-step explanation: