Mathematics, 03.10.2019 00:30 ErrorNameTaken505

Correct answer only !

use technology or a z-score table to answer the question.

the lengths of green beans for sale at a supermarket are normally distributed with a mean of 11.2 centimeters and a standard deviation of 2.1 centimeters. consider a bag of 150 green beans.

how many green beans will be 13 centimeters or shorter?

Correct answer only ! use technology or a z-score table to answer the question.

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Answer from: jona187

Choice C: approximately 121 green beans will be 13 centimeters or shorter.

Step-by-step explanation:

What's the probability that a green bean from this sale is shorter than 13 centimeters?

Let the length of a green bean be centimeters.

follows a normal distribution with

mean $\mu = 11.2$ and standard deviation $\sigma = 2.1$ .

In other words,

$X\sim \text{N}(11.2, 2.1^{2})$ ,

and the probability in question is $X \le 13$ .

Z-score table approach:

Find the z-score of this measurement:

$\displaystyle z= \frac{x-\mu}{\sigma} = \frac{13-11.2}{2.1} = 0.857143$ . Closest to 0.86.

Look up the z-score in a table. Keep in mind that entries on a typical z-score table gives the probability of the left tail, which is the chance that will be less than or equal to the z-score in question. (In case the question is asking for the probability that is greater than the z-score, subtract the value from table from 1.)

$P(X\le 13) = P(Z \le 0.857143) \approx 0.8051$ .

"Technology" Approach

Depending on the manufacturer, the steps generally include:

Locate the cumulative probability function (cdf) for normal distributions.Enter the lower and upper bound. The lower bound shall be a very negative number such as $-10^{9}$ . For the upper bound, enter

Enter the mean and standard deviation (or variance if required).Evaluate.

For example, on a Texas Instruments TI-84, evaluating $\text{normalcdf})(-1\text{E}99,\;13,\;11.2,\;2.1 )$ gives 0.804317 .

As a result,

$P(X\le 13) = 0.804317$ .

Number of green beans that are shorter than 13 centimeters:

Assume that the length of green beans for sale are independent of each other. The probability that each green bean is shorter than 13 centimeters is constant. As a result, the number of green beans out of 150 that are shorter than 13 centimeters follow a binomial distribution.

Number of trials

: 150.Probability of success

: 0.804317.

Let be the number of green beans out of this 150 that are shorter than 13 centimeters. $Y\sim\text{B}(150,0.804317)$ .

The expected value of a binomial random variable is the product of the number of trials and the probability of success on each trial. In other words,

$E(Y) = n\cdot p = 150 \times 0.804317 = 120.648\approx 121$

The expected number of green beans out of this 150 that are shorter than 13 centimeters will thus be approximately 121.

Answer from: Quest

answer

the correct answer is

$x=-5,x=7$

explanation

the given function is

$\frac{ {x}^{2} - 3x - 28 }{x {}^{2} - 2x - 35}$

the excluded values are obtained by solving:

${x}^{2} - 2x - 35 = 0$

we factor to obtain:

$(x + 5)(x - 7)= 0$

the excluded values are

$x=-5,x=7$

What are the excluded values of x for.. (look at picture)

Answer from: Quest

step-by-step explanation:

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