Answer:
The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.
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 problem, we have that:

What is the reading speed of a sixth-grader whose reading speed is at the 90th percentile
This is the value of X when Z has a pvalue of 0.9. So it is X when Z = 1.28.




The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.
(a) Using the completing the square method, we need to write into the form of where , so
Expand to find the value of c
Notice that we get back the first two terms, the and the .We need to get rid of the last term of '9' as the term was not in the original form. The final form will look like
Hence,
(b)
(c) , square root both sides plus and minus of 2 Hence
Answer:
2
Step-by-step explanation:
The outlier here is greatly above all of the others, the mean is the sum of all of the numbers/the amount of numbers. So, if we exclude the outlier, the sum of all of the numbers would decrease
The answer is B because u always start of like that