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Most US adults have social ties with a large number of people, including friends, family, co-workers, and other acquaintances. I

xxTIMURxx [149]

Answer:

$t=\frac{669-634}{\frac{732}{\sqrt{1700}}}=1.971$

$p_v =2*P(t_{(1699)}>1.971)=0.049$

If we compare the p value and the significance level given $\alpha=0.1$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the true mean is different from 634 at 10% of signficance.

Step-by-step explanation:

Data given and notation

$\bar X=669$ represent the sample mean

$s=732$ represent the sample standard deviation

$n=1700$ sample size

$\mu_o =68$ represent the value that we want to test

$\alpha=0.$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is different from 634, the system of hypothesis would be:

Null hypothesis: $\mu = 634$

Alternative hypothesis: $\mu \neq 634$

If we analyze the size for the sample is > 30 but we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{669-634}{\frac{732}{\sqrt{1700}}}=1.971$

P-value

The first step is calculate the degrees of freedom, on this case:

$df=n-1=1700-1=1699$

Since is a two sided test the p value would be:

$p_v =2*P(t_{(1699)}>1.971)=0.049$

Conclusion

If we compare the p value and the significance level given $\alpha=0.1$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the true mean is different from 634 at 10% of signficance.

3 0

2 years ago

In 1898 L. J. Bortkiewicz published a book entitled The Law of Small Numbers. He used data collected over 20 years to show that

attashe74 [19]

Answer:

(a) The probability of more than one death in a corps in a year is 0.1252.

(b) The probability of no deaths in a corps over 7 years is 0.0130.

Step-by-step explanation:

Let X = number of soldiers killed by horse kicks in 1 year.

The random variable $X\sim Poisson(\lambda = 0.62)$ .

The probability function of a Poisson distribution is:

$P(X=x)=\frac{e^{-\lambda}\lambda^{x}}{x!};\ x=0,1,2,...$

(a)

Compute the probability of more than one death in a corps in a year as follows:

P (X > 1) = 1 - P (X ≤ 1)

= 1 - P (X = 0) - P (X = 1)

$=1-\frac{e^{-0.62}(0.62)^{0}}{0!}-\frac{e^{-0.62}(0.62)^{1}}{1!}\\=1-0.54335-0.33144\\=0.12521\\\approx0.1252$

Thus, the probability of more than one death in a corps in a year is 0.1252.

(b)

The average deaths over 7 year period is: $\lambda=7\times0.62=4.34$

Compute the probability of no deaths in a corps over 7 years as follows:

$P(X=0)=\frac{e^{-4.34}(4.34)^{0}}{0!}=0.01304\approx0.0130$

Thus, the probability of no deaths in a corps over 7 years is 0.0130.

6 0

1 year ago

What is Question I (if m<EBF = 117°, fine m<ABE)

Natasha_Volkova [10]

Answer:

m∠ABE = 27°

Step-by-step explanation:

* Lets look to the figure to solve the problem

- AC is a line

- Ray BF intersects the line AC at B

- Ray BF ⊥ line AC

∴ ∠ABF and ∠CBF are right angles

∴ m∠ABF = m∠CBF = 90°

- Rays BE and BD intersect the line AC at B

∵ m∠ABE = m∠DBE ⇒ have same symbol on the figure

∴ BE is the bisector of angle ABD

∵ m∠EBF = 117°

∵ m∠EBF = m∠ABE + m∠ABF

∵ m∠ABF = 90°

∴ 117° = m∠ABE + 90°

- Subtract 90 from both sides

∴ m∠ABE = 27°

4 0

2 years ago

Read 2 more answers

The equation A(t) = 900(0.85)t represents the value of a motor scooter t years after it was purchased. Which statements are also

ValentinkaMS [17]

Answer:

When new, the scooter cost $900

Step-by-step explanation:

The complete question in the attached figure

we have

$A(t)=900(0.85)^t$

This is a exponential function of the form

$A(t)=a(b)^t$

where

A(t) ----> represent the value of a motor scooter

t ----> the number of years after it was purchased

a ---> represent the initial value or y-intercept

b is the base of the exponential function

r is the percent rate of change

b=(1+r)

In this problem we have

$a=\$900\\b=0.85$

The base b is less than 1

That means ----> is a exponential decay function (is a decreasing function)

Find the percent rate of change

$b=(1+r)\\0.85=1+r\\r=0.85-1\\r=-0.15$

Convert to percentage (multiply by 100)

$r=-15\%$ ---> negative means is a decreasing function

Verify each statements

case A) When new, the scooter cost $765.

The statement is false

Because the original value of the scooter was $900

case B) When new, the scooter cost $900

The statement is true (see the explanation)

case C) The scooter’s value is decreasing at a rate of 85% each year

The statement is false

Because the scooter’s value is decreasing at a rate of 15% each year (see the explanation)

case D) The scooter’s value is decreasing at a rate of 0.15% each year

The statement is false

Because the scooter’s value is decreasing at a rate of 15% each year (see the explanation)

8 0

2 years ago

The tables show the relationships between x and y for two data sets. Data Set Data Set I X 5.5 1 Z 11.0 2 10 5 165 3 15 220 2D 5

notka56 [123]

Answer:

C I beleive the answer is C Both data sets show multiplicative relationships.

In Data Set I, y is 5.5 times x, and in Data Set II, y is 5 times x.

Step-by-step explanation:

I beleive the answer it C thank you bye bye have a nice day hope this helped

5 0

1 year ago

Read 2 more answers