Answer:
Shirts = $7
Shorts $17
Step-by-step explanation:
Let:
T - shirts
S - shorts
We can make two equations out of this problem:
4T + 3S = $79
7T + 8S = $185
Through substitution we can solve for one of the unknowns. We make one equation to solve for an unknown
We use the formula of S and insert it into the other equation:
Thus T-shirts are $7 each.
Now that we know T, we can use it to solve for the other unknown. You can use it on any of the formulas.
We know then that Shorts are $17 each.
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.
