D = r• t
reverses the equation so that D and r are on the same side
d/r = t
Sam travels 4 hours at a rate of 50 mph
reverses the equation so that D and r are on the same side
d/r = t
Sam travels 4 hours at a rate of 50 mph
48. Reading Rates The reading speed of sixth-grade students is approximately normal, with a mean speed of 125 words per minute a
2 answers:
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.
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Answer:
see attached diagram
Step-by-step explanation:
First, draw the dashed line 50x+150y=1500 (dashed because the inequality is without notion "or equal to"). You can do it finding x and y intercepts.
When x=0, then 150y=1500, y=10.
When y=0, then 50x=1500, x=30.
Connect points (0,10) and (30,0) to get needed dashed line.
Then determine which region (semiplane) you have to choose. Note that origin's coordinates (0,0) do not satisfy the inequality 50x + 150y>1500, because
This means that origin lies outside the needed region, so you have to choose the semiplane that do not contain origin (see attached diagram).
Answer:
Should be the answer