All categories

3 years ago

What is the definition of mean???

1 answer:

3 0

Mean, in terms of math, is the total added values of all the data in a set divided by the number of data <em>in</em> the set. Make sense? If not, here' an example...

Let's say this is my data set:
1, 2, 5, 4, 3, 8, 7, 4, 6,10

To find the mean...
Step 1: Add all of them together.
1+2+5+4+3+8+7+4+6+10 is what? 50. Now that you have this number...
Step 2: Divide by the amount there are. Basically, count up all of the numbers. How many are there? There are 10. Finally...
Step 3: Divide. 50/10 is 5, so the mean of this data set would be 5. Get it? I sure hoped this helped :)

You might be interested in

A self proclaimed psychic was tested for ESP. The psychic was presented with 200 cards face down and asked to determine if the c

swat32

Answer:

The 95% confidence interval would be given (0.172;0.288).

We are confident at 95% that the true probability that the psychic correctly identifies the symbol on the card in a random trial is between (0.172;0.288).

We can conclude that her random guessing would have got her correct 20% of the time. Since the confidence interval contains 0.2, she has no psychic powers, rather she just guessed it like normal people. Any person could have got it correct this many times.

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".

Description in words of the parameter p

$p$ represent the probability that the psychic correctly identifies the symbol on the card in a random trial

$\hat p$ represent the estimated probability that the psychic correctly identifies the symbol on the card in a random trial

n=200 is the sample size required

$z_{\alpha/2}$ represent the critical value for the margin of error

The population proportion have the following distribution

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

Numerical estimate for p

In order to estimate a proportion we use this formula:

$\hat p =\frac{X}{n}$ where X represent the cases successful

$\hat p=\frac{46}{200}=0.23$ represent the estimated probability that the psychic correctly identifies the symbol on the card in a random trial

Confidence interval

The confidence interval for a proportion is given by this formula:

$\hat p \pm z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}$

For the 95% confidence interval the value of $\alpha=1-0.95=0.05$ and $\alpha/2=0.025$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=1.96$

And replacing into the confidence interval formula we got:

$0.23 - 1.96 \sqrt{\frac{0.23(1-0.23)}{200}}=0.172$

$0.23 + 1.96 \sqrt{\frac{0.23(1-0.23)}{200}}=0.288$

And the 95% confidence interval would be given (0.172;0.288).

We are confident at 95% that the true probability that the psychic correctly identifies the symbol on the card in a random trial is between (0.172;0.288).

6 0

3 years ago

The table gives estimates of the world population, in millions, from 1750 to 2000. (Round your answers to the nearest million.)

BaLLatris [955]

Answer:

A.) 1508 ; 1870

B.) 2083

C.) 3972

Step-by-step explanation:

General form of an exponential model :

A = A0e^rt

A0 = initial population

A = final population

r = growth rate ; t = time

Using the year 1750 and 1800

Time, t = 1800 - 1750 = 50 years

Initial population = 790

Final population = 980

Let's obtain the growth rate :

980 = 790e^50r

980/790 = e^50r

Take the In of both sides

In(980/790) = 50r

0.2155196 = 50r

r = 0.2155196/50

r = 0.0043103

Using this rate, let predict the population in 1900

t = 1900 - 1750 = 150 years

A = 790e^150*0.0043103

A = 790e^0.6465588

A = 1508.0788 ; 1508 million people

In 1950;

t = 1950 - 1750 = 200

A = 790e^200*0.0043103

A = 790e^0.86206

A = 1870.7467 ; 1870 million people

2.)

Exponential model. For 1800 and 1850

Initial, 1800 = 980

Final, 1850 = 1260

t = 1850 - 1800 = 50

Using the exponential format ; we can obtain the rate :

1260 = 980e^50r

1260/980 = e^50r

Take the In of both sides

In(1260/980) = 50r

0.2513144 = 50r

r = 0.2513144/50

r = 0.0050262

Using the model ; The predicted population in 1950;

In 1950;

t = 1950 - 1800 = 150

A = 980e^150*0.0050262

A = 980e^0.7539432

A = 2082.8571 ; 2083 million people

3.)

1900 1650

1950 2560

t = 1900 - 1950 = 50

Using the exponential format ; we can obtain the rate :

2560 = 1650e^50r

2560/1650 = e^50r

Take the In of both sides

In(2560/1650) = 50r

0.4392319 = 50r

r = 0.4392319/50

r = 0.0087846

Using the model ; The predicted population in 2000;

In 2000;

t = 2000 - 1900 = 100

A = 1650e^100*0.0087846

A = 1650e^0.8784639

A = 3971.8787 ; 3972 million people

3 0

3 years ago

At a certain school,5/9 of the students are boys. Today, 2/3 of the boys brought their lunch. What fraction of the students are

Elodia [21]

5/6 of the boys brought their lunch.

In order to determine the answer you need to divide 5/9 by 2/3 in which will give you 5/6.

4 0

3 years ago

Can somebody answer this ?? :)

Alexxandr [17]

Answer:

Because the dashed triangle is smaller than the original it's a reduction. The scale factor is 1/3 because if we look at the altitudes of the triangle, the original is 6 and the dilated is 2 and 2 / 6 = 1 / 3.

4 0

3 years ago

Could someone please help me solve this?

ryzh [129]

Answer:

Step-by-step explanation:

(2/5)*n - 6 = 10 Add 6 to both sides

(2/5)*n - 6 + 6 = 10 + 6 Combine

(2/5)*n = 16 Multiply both sides by 5/2

(5/2)(2/5)n = 16*(5/2)

n = 80 / 2

n = 40

6 0

3 years ago