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.
Answer:
A = 92y + 81
Step-by-step explanation:
Because A = number of attendees and if it adds 92 each year, you times the number of years by 92 and add 81 for the ones that were already there
Answer:
70
Step-by-step explanation:
Apparently, you want the ratio of the weights:
(dino weight)/(car weight) = (2.8×10^5)/(4×10^3)
= (2.8/4)×10^(5-3) = 0.7×10^2 = 0.7×100
= 70
The heaviest dinosaur weighed about 70 times the weight of an average car.
_____
Your calculator can do arithmetic in scientific notation. So can any spreadsheet.
The applicable rule of exponents is ...
(10^a)/(10^b) = 10^(a-b)
First bring them to common denominator.