Mathematics, 21.02.2020 00:58 izzyisawesome5232

The grades on a physics midterm at Covington have an average of μ=72 and σ=2.0 If Stephanie scored 1.23 standard deviations above the mean.

a. What score did Stephanie get on the exam?
b. What percent of students scored better than Stephanie?

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Answer from: sugaree95

a) She scored 74.46 on the exam.

b) 11% of the students scored better than Stephanie.

Step-by-step explanation:

The z-score measures how many standard deviation a score X is above or below the mean. It is given by the following formula:

$Z = \frac{X - \mu}{\sigma}$

In which $\mu$ is the mean and $\sigma$ is the standard deviation.

In this problem, we have that:

$\mu = 72, \sigma = 2$

a. What score did Stephanie get on the exam?

Stephanie scored 1.23 standard deviations above the mean. This means that her z-score is Z = 1.23

We want to find X

$Z = \frac{X - \mu}{\sigma}$

$1.23 = \frac{X - 72}{2}$

X - 72 = 2*1.23

X = 74.46

She scored 74.46 on the exam.

b. What percent of students scored better than Stephanie?

Each z-score has a pvalue, which is the percentile of the score. We look this pvalue at the z table.

Z = 1.23 has a pvalue of 0.89.

This means that Stephanie's score is in the 89th percentile, which means that she scored more than 89% of the students and scored less than 100-89 = 11% of the students.

So 11% of the students scored better than Stephanie.

Answer from: Quest

step-by-step explanation:

a. since the profit made in 2012 is equal to the profit made in 2014, the profit is symmetric about the line y = 120,000.

step-by-step explanation:

given that megan owns a clothing boutique.

the profits of 2010, 11, are recorded and shown as follows:

years since 2010 0 1 2 3 4 5

profits made in 1000's 39 84 111 120 111 84

we find that profit gradually increases form 2010 to 2013 upto 120, then starts decreasing.

the profits for 2012 and 2014 are the same while that of 2011 and 2015 are also the same.

this shows that there is symmetry about the line profit = 120000

hence answer is:

a. since the profit made in 2012 is equal to the profit made in 2014, the profit is symmetric about the line y = 120,000.

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