21 is the right answer goodluck
The value of z-score for a score that is three standard deviations above the mean is 3.
In this question,
A z-score measures exactly how many standard deviations a data point is above or below the mean. It allows us to calculate the probability of a score occurring within our normal distribution and enables us to compare two scores that are from different normal distributions.
Let x be the score
let μ be the mean and
let σ be the standard deviations
Now, x = μ + 3σ
The formula of z-score is
⇒
⇒
⇒
Hence we can conclude that the value of z-score for a score that is three standard deviations above the mean is 3.
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B. Angle 2 and angle seven are actually alternate exterior angles.
The number of ways in which you can win first prize and your mom went the second prize will be 8. Then the correct option is D.
<h3>What are permutation and combination?</h3>
A permutation is an act of putting things or elements in the right sequence. Combinations are a method of picking things or pieces from a collection of objects or sets when the sequence of the objects is irrelevant.
You and your mom enter the drawing with three different prices the prizes are awarded at random is a total of 8 people entered the drawing.
Then the number of the ways in which you can win first prize and your mom went the second prize will be
Let x be the number of different ways.
Then we have
Thus, the number of ways in which you can win first prize and your mom went the second prize will be 8.
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