What is the rule 60/70 and 670/680

4- A manufacturing process produces items whose weights are normally distributed. It is known that 22.57% of all the items produ

galben [10]

Answer:

$\\ \mu = 118\;grams\;and\;\sigma=30\;grams$

Step-by-step explanation:

We need to use z-scores and a standard normal table to find the values that corresponds to the probabilities given, and then to solve a system of equations to find $\\ \mu\;and\;\sigma$ .

<h3>First Case: items from 100 grams to the mean</h3>

For finding probabilities that corresponds to z-scores, we are going to use here a <u>Standard Normal Table </u><u><em>for cumulative probabilities from the mean </em></u><em>(Standard normal table. Cumulative from the mean (0 to Z), 2020, in Wikipedia) </em>that is, the "probability that a statistic is between 0 (the mean) and Z".

A value of a z-score for the probability P(100<x<mean) = 22.57% = 0.2257 corresponds to a value of z-score = 0.6, that is, the value is 0.6 standard deviations from the mean. Since this value is <em>below the mean</em> ("the items produced weigh between 100 grams up to the mean"), then the z-score is negative.

Then

$\\ z = -0.6\;and\;z = \frac{x-\mu}{\sigma}$

$\\ -0.6 = \frac{100-\mu}{\sigma}$ (1)

<h3>Second Case: items from the mean up to 190 grams</h3>

We can apply the same procedure as before. A value of a z-score for the probability P(mean<x<190) = 49.18% = 0.4918 corresponds to a value of z-score = 2.4, which is positive since it is after the mean.

Then

$\\ z =2.4\;and\; z = \frac{x-\mu}{\sigma}$

$\\ 2.4 = \frac{190-\mu}{\sigma}$ (2)

<h3>Solving a system of equations for values of the mean and standard deviation</h3>

Having equations (1) and (2), we can form a system of two equations and two unknowns values:

$\\ -0.6 = \frac{100-\mu}{\sigma}$ (1)

$\\ 2.4 = \frac{190-\mu}{\sigma}$ (2)

Rearranging these two equations:

$\\ -0.6*\sigma = 100-\mu$ (1)

$\\ 2.4*\sigma = 190-\mu$ (2)

To solve this system of equations, we can multiply (1) by -1, and them sum the two resulting equation:

$\\ 0.6*\sigma = -100+\mu$ (1)

$\\ 2.4*\sigma = 190-\mu$ (2)

Summing both equations, we obtain the following equation:

$\\ 3.0*\sigma = 90$

Then

$\\ \sigma = \frac{90}{3.0} = 30$

To find the value of the mean, we need to substitute the value obtained for the standard deviation in equation (2):

$\\ 2.4*30 = 190-\mu$ (2)

$\\ 2.4*30 - 190 = -\mu$

$\\ -2.4*30 + 190 = \mu$

$\\ \mu = 118$

7 0

2 years ago

1/4 of 24 on tape diagram

Lemur [1.5K]

Draw the tape diagram: a long rectangle and divide it into 4 squares in a row.The whole rectangle represents 24 (as a whole number), you're dividing it into 4 parts because you want to know what is 1/4 of it.Now, to find the value of each square: 24:4 = 6.Put the number 6 in each square, and you have found your result.1/4 of 24 is 6.

8 0

3 years ago

Lynn is making custom bricks. She combines 39 pounds of water and 48 pounds of brick dust

vova2212 [387]

Answer:

10, and 4.

Step-by-step explanation:

39+48=87

87-13=74

74 divided by 7= 10 R4

Greatest amount of bricks= 10

Leftovers= 4.

5 0

2 years ago

How do i write a two column proof for this??<br><br>Given: PG ≅ SG and PT ≅ ST . Prove: ∠GPT ≅ ∠GST

Nikolay [14]

Answer:

PG ≅ SG (Given)

PT ≅ ST (Given)

GT = GT (Common)

∴ ∠GPT ≅ ∠GST (SSS Congruency Axiom)

Step-by-step explanation:

<u>Given</u>: PG ≅ SG and PT ≅ ST

<u>To Prove</u>: ∠GPT ≅ ∠GST

<u>Proof</u>: PG ≅ SG (Given)

PT ≅ ST (Given)

GT = GT (Common)

∴ ∠GPT ≅ ∠GST (SSS Congruency Axiom).

<u>SSS Congruency Axiom</u>: If three pairs of sides of two triangles are equal in length, then the triangles are congruent.

<u>Congruence</u>: Two sets of points are called congruent if, and only if, one can be transformed into the other by an isometry, i.e., a combination of rigid motions, namely a translation, a rotation, and a reflection. This means that either object can be repositioned and reflected (but not resized) so as to coincide precisely with the other object. Two triangles are congruent if their corresponding sides are equal in length, and their corresponding angles are equal in measure.

7 0

3 years ago

Which phrases can be represented by the algebraic expression x + 14? Select three options.

Snezhnost [94]

Answer:

a number plus 14

fourteen more than a number

a number increased by 14

Step-by-step explanation:

The phrases which can be represented by the algebraic expression x + 14 are

Let x = the unknown number

a number plus 14

= x + 14

fourteen more than a number

= x + 14

a number increased by 14

x + 14

4 0

2 years ago

Read 2 more answers