When a willow tree was planted it was 24 inches tall. Three years later, the tree was

Life Expectancies In a study of the life expectancy of people in a certain geographic region, the mean age at death was years an

Sphinxa [80]

Answer:

The probability that the mean life expectancy of the sample is less than X years is the p-value of $Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$ , in which $\mu$ is the mean life expectancy, $\sigma$ is the standard deviation and n is the size of the sample.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

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.

Central Limit Theorem

The Central Limit Theorem establishes 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 $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

We have:

Mean $\mu$ , standard deviation $\sigma$ .

Sample of size n:

This means that the z-score is now, by the Central Limit Theorem:

$Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$

Find the probability that the mean life expectancy will be less than years.

The probability that the mean life expectancy of the sample is less than X years is the p-value of $Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$ , in which $\mu$ is the mean life expectancy, $\sigma$ is the standard deviation and n is the size of the sample.

8 0

2 years ago

How do I find cube roots

anyanavicka [17]

Answer:

Step-by-step explanation:

5-500 is sqare 5

6 0

3 years ago

A rectangle has a height of 7x^2and a width of 3x^2+ 8x + 7.

Anika [276]

Answer:

Step-by-step explanation:

8 0

3 years ago

You have$560 in an account which pays 4.8% compounded annually. If you invest your money for 8 years, then how many dollars of i

SCORPION-xisa [38]

Answer:

$ 254.85

Step-by-step explanation:

Total amount invested = $ 560

Interest rate = r = 4.8% = 0.048

Time in years = t = 8 years

The formula for compound interest is:

$A =P(1+\frac{r}{n})^{nt}$

Here,

A is the total amount accumulated after t years. P is the amount invested initially and n is the compounding periods per year. Since in this case compounding is done annually, n will be 1. Using the values in the above formula, we get:

$A=560(1+\frac{0.048}{1})^{8} = \$ 814.85$

Thus, the total amount accumulated after 8 years will be $ 814.85

The amount of interest earned will be:

Interest = Amount Accumulated - Principal Amount

Interest = $ 814.85 - $ 560 = $ 254.85

By the end of 8 years, $ 254.85 would be earned in interest.

7 0

3 years ago

Which angles are linear pairs? Check all that apply

dangina [55]

Answer:

A linear pair of angles is formed when two lines intersect. Two angles are said to be linear if they are adjacent angles formed by two intersecting lines. The measure of a straight angle is 180 degrees, so a linear pair of angles must add up to 180 degrees.

8 0

3 years ago