Help me please I will give u 100 points and brainliest

Terri gets most of her exercise by walking briskly. Last year she walked an average of 4.2 miles per day with a standard deviati

Alinara [238K]

Terri walked in her own 93rd percentile, while April swam in her own 99th percentile. April is off to a slightly better start.

3 0

3 years ago

A random sample of 77 fields of corn has a mean yield of 26.226.2 bushels per acre and standard deviation of 2.322.32 bushels pe

PSYCHO15rus [73]

Answer:

Therefore the 95% confidence interval is (25,707.480 < E < 26,744.920)

Step-by-step explanation:

n = 77

mean u = 26,226.2 bushels per acre

standard deviation s = 2,322.32

let E = true mean

let A = test statistic

Find 95% Confidence Interval

so

let A = (u - E) * ( $\sqrt{n}$ / s) be the test statistic

we want P( average_l < A < average_u ) = 95%

look for lower 2.5% and the upper 97.5% Because I think this is a 2-tail test

average_l = -1.96 which corresponds to the 2.5%

average_u = 1.96

P( -1.96 < A < 1.96) = 95%

P( -1.96 < (u - E) * ( $\sqrt{n}$ / s) < 1.96) = 95%

Solve for the true mean E ok

E < u + 1.96* (s / $\sqrt{n}$ )

from -1.96 < (u - E) * ( $\sqrt{n}$ / s)

E < 26,226.2 + 1.96*( 2,322.32 / $\sqrt{77}$ )

E < 26,226.2 + 518.7197348105429466

upper bound is 26,744.9197

or

u - 1.96* (s / $\sqrt{n}$ ) < E

26,226.2 - 518.7197348105429466 < E

25,707.48026519 < E

lower bound is 25,707.48026519

Therefore the 95% confidence interval is (25,707.480 < E < 26,744.920)

7 0

3 years ago

What is the benefit of dividing out greatest common factors (GCFs) before multiplying?

Nina [5.8K]

Lets get an example, for this example lets use 24/30 x 30/60
Without dividing out GCFs you would get 24x12 over 30 x 60 which is 288/1800
With dividing out GCFs you get 2/1 x 5/1 Which is 7 :)

7 0

3 years ago

Read 2 more answers

A fruit stand has 28 apples, 20 oranges, and 12 pears. What is the ratio of apples to the total pieces of fruit?

ruslelena [56]

Data:
Apples = 28
Oranges = 20
Pears = 12

<span>What is the ratio of apples to the total pieces of fruit?
Solving:
</span> $\frac{apples}{apples+oranges+pears} = \frac{28}{28+20+12} = \frac{28}{60} \frac{\div4}{\div4} \to\:\boxed{\boxed{ratio = \frac{7}{15}}}\end{array}}\qquad\quad\checkmark$ <span>
</span>

5 0

3 years ago

A researcher reports survey results by stating that the standard error of the mean is 25 the population standard deviation is 40

bezimeni [28]

Answer:

a) A sample of 256 was used in this survey.

b) 45.14% probability that the point estimate was within ±15 of the population mean

Step-by-step explanation:

This question is solved using the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use the z-score formula.

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.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .