Answer:
The percentage of students who scored below 620 is 93.32%.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:

Percentage of students who scored below 620:
This is the pvalue of Z when X = 620. So



has a pvalue of 0.9332
The percentage of students who scored below 620 is 93.32%.
Answer:
3. is 3 (m - 16)(m + 4)
7. is also 3. (2x + 5)(3x - 5)
12. is 4 (x - 6)(x - 4)
the last one is i dont know
-2x + 6 + 6x = 6 (2x - 3) <em>this is the equation</em>
-2x + 6 + 6x = 12x - 18 <em>distributive property has been applied</em>
4x + 6 = 12x - 18 <em>like terms have been added</em>
6 = 8x -18 <em>4x has been</em><em> </em><em>subtracted from both sides</em>
24 = 8x <em>-18 has been added to both sides</em>
3 = x <em>8 has been divided from both sides</em>
<em></em>
I hope this helps! Let me know if I need to explain more or if I got something wrong. Have a nice day!