In ΔCDE, the measure of ∠E=90°, the measure of ∠C=83°, and DE = 8.6 feet. Find the length of EC to the nearest tenth of a foot.

Suppose a 90% confidence interval for the mean salary of college graduates in a town in Mississippi is given by [$38,737, $50,46

JulsSmile [24]

Answer:

a. The point estimate was of $44,600.

b. The sample size was of 16.

Step-by-step explanation:

Confidence interval concepts:

A confidence interval has two bounds, a lower bound and an upper bound.

A confidence interval is symmetric, which means that the point estimate used is the mid point between these two bounds, that is, the mean of the two bounds.

The margin of error is the difference between the two bounds, divided by 2.

a. What is the point estimate of the mean salary for all college graduates in this town?

Mean of the bounds, so:

(38737+50463)/2 = 44600.

The point estimate was of $44,600.

b. Determine the sample size used for the analysis.

First we need to find the margin of error, so:

$M = \frac{50463-38737}{2} = 5863$

Relating the margin of error with the sample size:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.9}{2} = 0.05$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.05 = 0.95$ , so Z = 1.64.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

For this problem, we have that $\sigma = 14300, M = 5863$ . So

$M = z\frac{\sigma}{\sqrt{n}}$

$5863 = 1.645\frac{14300}{\sqrt{n}}$

$5863\sqrt{n} = 1.645*14300$

$\sqrt{n} = \frac{1.645*14300}{5863}$

$(\sqrt{n})^2 = (\frac{1.645*14300}{5863})^2$

$n = 16$

The sample size was of 16.

7 0

2 years ago

Aristotle was born in 384 BC. Ron Howard was born in 1952 AD. HOW many years apart were they born?

rodikova [14]

The answer is 2336 cause bc was before Christ ad us after death so if we add them that's the answer

6 0

3 years ago

Two trains 100 km apart are traveling toward each other along the same track. The first train goes 50 km per hour; the second tr

dem82 [27]

Answer:

92.31 km

Step-by-step explanation:

Combined speed = 50+80

= 130 km/hour

Time = 100/130 = 10/13 hours to collide

Speed × time = distance

distance = 10/13 × 120

= 92.30769231 km

7 0

2 years ago

The graph of f(x) is shown. which graph represents g(x) = f(2x)

Temka [501]

A because its twice bigger than the real one

5 0

2 years ago

Read 2 more answers

The lengths of bolts in a batch are distributed normally with a mean of 3 cm and a standard

ValentinkaMS [17]

Answer:

0.8413 = 84.13% probability that a bolt has a length greater than 2.96 cm.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Mean of 3 cm and a standard deviation of 0.04 cm.

This means that $\mu = 3, \sigma = 0.04$