Answer:
28
Step-by-step explanation:
25+26+27+28=106
Answer:

Step-by-step explanation:

When x = 4,

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:
It has a maximum
Step-by-step explanation:
The way I think about it is looking at "a" (the leading variable's coefficient, so __x²), if it's negative, the graph is a frown, but if it's positive, it's a smile. In this case, a is -2, so the graph would have the shape of a frown, which has a maximum.
I hope this helped!