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:
Step-by-step explanation:
remove the parenthesis
5x+10=20
5x+10-10=20-10
5x=10
x=2
She bought 8 bags of candy since 10 multiplied by eight is 80 and 8 is two less than ten.(ten candies in each bag)
Answer:
1 hour and 45 minutes
and 1 hour
Step-by-step explanation:
x= run
y= walk
5x+2.5y = distance
5x+2.5(1.5)=12.5
solve for x
5x=8.75
x=1.75
1.75 in hours is 1 hour and (60*.75)=45
1 hour and 45 minutes
" If the marathon race participant ran for 2 hours, how many hours did the participant walk?"
We use the same equation
5x+2.5y=distance
we'll assume that they till walked 12.5 miles
which means that
5(2)+2.5y=12.5
solve for y
2.5=2.5y
y=1
1 hour