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olya-2409 [2.1K]
2 years ago
5

Scores on Ms. Bond's test have a mean of 70 and a standard deviation of 11. David has a score of 52 on Ms. Bond's test. Scores o

n Ms. Nash's test have a mean of 64 and a standard deviation of 6. Steven has a score of 52 on Ms. Nash's test. Which student has the higher standardized score
Mathematics
1 answer:
otez555 [7]2 years ago
3 0

Answer:

Due to the higher z-score, David has the higher standardized score

Step-by-step explanation:

Z-score:

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

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

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.

Which student has the higher standardized score

Whoever had the higher z-score.

David:

Scores on Ms. Bond's test have a mean of 70 and a standard deviation of 11. David has a score of 52 on Ms. Bond's test. So X = 52, \mu = 70, \sigma = 11

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

Z = \frac{52 - 70}{11}

Z = -1.64

Steven:

Scores on Ms. Nash's test have a mean of 64 and a standard deviation of 6. Steven has a score of 52 on Ms. So X = 52, \mu = 64, \sigma = 6

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

Z = \frac{52 - 64}{6}

Z = -2

Due to the higher z-score, David has the higher standardized score

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Doug purchased land for $8,000 in 1995. The year value of the land depreciated by 4% each year thereafter. Use an exponential fu
Marta_Voda [28]

Answer:

Option C. $6,012

Step-by-step explanation:

we know that

The  formula to calculate the depreciated value  is equal to

V=P(1-r)^{t}

where  

V is the the depreciated value  

P is the original value  

r is the rate of depreciation  in decimal

t is Number of Time Periods  

in this problem we have  

t = 7 years

P = $8,000

r = 0.04

substitute in the formula above

V = 8,000(1-0.04)^{7} = 6,012

Hope this helps :)

4 0
2 years ago
It is believed that as many as 23% of adults over 50 never graduated from high school. We wish to see if this percentage is the
JulijaS [17]

Answer:

1)  n=48  

2) n=298

3) n=426

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".  

p represent the real population proportion of interest

\hat p represent the estimated proportion for the sample

n is the sample size required (variable of interest)

z represent the critical value for the margin of error

The population proportion have the following distribution  

p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})  

Part 1

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by \alpha=1-0.90=0.10 and \alpha/2 =0.05. And the critical value would be given by:  

z_{\alpha/2}=-1.64, z_{1-\alpha/2}=1.64  

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}} (a)  

And on this case we have that ME =\pm 0.1 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2} (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:  

n=\frac{0.23(1-0.23)}{(\frac{0.1}{1.64})^2}=47.63  

And rounded up we have that n=48  

Part 2

The margin of error on this case changes to 0.04 so if we use the same formula but changing the value for ME we got:

n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.64})^2}=297.7  

And rounded up we have that n=298  

Part 3

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical value would be given by:  

z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96  

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}} (a)  

And on this case we have that ME =\pm 0.04 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2} (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:  

n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.96})^2}=425.22  

And rounded up we have that n=426  

3 0
2 years ago
the ratio of the measures of the sides of a triangle is 21:8:14 if the perimeter of the triangle is 215 feet find the length of
SOVA2 [1]

Answer:

the 3 sides of the triangle are 105 ft, 40 ft and 70 ft.

Step-by-step explanation:

the perimeter is the sum of the 3 sides of the triangle

add the parts of the ratio 21 + 8 + 14 = 43

divide the perimeter by 43 to find the value of one part of the ratio

= 5 ft ← 1 part of the ratio, hence

21 parts = 21 × 5 = 105 ft

8 parts = 8 × 5 = 40 ft

14 parts = 14 × 5 = 70 ft

the 3 sides of the triangle are 105 ft, 40 ft and 70 ft

6 0
2 years ago
The two-way frequency table below shows data on student behavior and the use of positive phone calls home as an incentive for go
dusya [7]

Answer:

From the frequency table, let's calculate the row total.

Row total for phone call = 19 + 9 = 28

Row total for no phone call = 8 +6 = 14

To calculate their respective row relative frequencies, let's use:

Row relative freq = \frac{freq.}{Row total}

Now, the two-way frequency table will be computed as:

For phone call:

Desirable behavior = \frac{19}{28} = 0.67857 ≈0.69

Undesirable behaviour = \frac{9}{28} = 0.3214 ≈0.32

No phone call:

Desirable behaviour = \frac{8}{14} = 0.5714 ≈ 0.57

Undesirable behaviour = \frac{6}{14} = 0.4286 ≈ 0.43

The complete two-way table is attached.

8 0
2 years ago
A hyperbola centered at the origin has a vertex at (0, 36) and a focus at (0, 39).
likoan [24]
To solve this problem you must apply the proccedure shown below:
 1. You have that the hyperbola <span>has a vertex at (0,36) and a focus at (0,39).
 2. Therefore, the equation of the directrices is:

 a=36
 a^2=1296
 c=39

 y=a^2/c

 3. When you susbtitute the values of a^2 and c into </span>y=a^2/c, you obtain:
<span>
 </span>y=a^2/c
<span> y=1296/13

 4. When you simplify:

 y=432/13

 Therefore, the answer is: </span><span>y = ±432/13</span>
4 0
2 years ago
Read 2 more answers
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