1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
san4es73 [151]
3 years ago
12

A process produces batches of a chemical whose impurity concentrations follow a normal distribution with a variance of175. A ran

dom sample of 20 of these batches is chosen. Find the probability that the sample variance exceeds 3.10.
Mathematics
2 answers:
Tom [10]3 years ago
8 0

Answer:

the probability that the sample variance exceeds 3.10 is 0.02020 ( 2,02%)

Step-by-step explanation:

since the variance  S² of the batch follows a normal distribution , then for a sample n of  20 distributions , then the random variable Z:

Z= S²*(n-1)/σ²

follows a χ² ( chi-squared) distribution with (n-1) degrees of freedom

since

S² > 3.10 , σ²= 1.75 , n= 20

thus

Z > 33.65

then from χ² distribution tables:

P(Z > 33.65) = 0.02020

therefore the probability that the sample variance exceeds 3.10 is 0.02020 ( 2,02%)

Arisa [49]3 years ago
5 0

Answer:

P(s^2 >3.10) =P(\frac{(n-1)s^2}{\sigma^2}>\frac{19*3.10}{1.75})

P(chi^2_{19}>33.657)=1-P(\chi^2_{19]

Step-by-step explanation:

Previous concepts

The Chi Square distribution is the distribution of the sum of squared standard normal deviates .

Data given and notation

For this case we can use the fact that the estimator of the population variance \sigma is the sample variance s^2, because E(s^2)=\sigma^2

The proof is this one:

Since E(\chi^2) = n-1 and

\chi^2 =\frac{(n-1) s^2}{\sigma^2}

When we take the expected value we got:

E[\frac{(n-1) s^2}{\sigma^2}]= n-1

E[s^2]=\frac{n-1}{n-1}\sigma^2

E[s^2]=\sigma^2

We have the distribution on this case given chi square.

Solution to the problem

The degrees of freddom on this case are given by

df=n-1=20-1=19

On this case we want this probability:

P(s^2 >3.10) =P(\frac{(n-1)s^2}{\sigma^2}>\frac{19*3.10}{1.75})

P(chi^2_{19}>33.657)=1-P(\chi^2_{19}

And we can use excel to find the probability with the following code:"=1-CHISQ.DIST(33.657,19,TRUE) "

You might be interested in
Anyone know the answer?
aivan3 [116]

Answer:

uhmmmmmm.... I also like 2048

Step-by-step explanation:

dcxadsfdzerwsfdtrxecdf

6 0
2 years ago
a term of scientists surveying a forest found that there were four oak trees for every 10 pine trees. if they counted 24 more pi
Jet001 [13]

Answer:

There are 16 Oak tree in the forest.

Step-by-step explanation:

Given: There are 4 Oak tree on every 10 pine trees.

           There are total 24 more pine tree than Oak tree.

 Using the ratio of trees to find the number of trees.

Lets assume there are total number of Oak tree be "x".

∴ Total number of Pine trees will be "x+24"

We know the ratio of Oak to Pine tree is 4:10 or \frac{4}{10}

⇒\frac{x}{x+24} = \frac{4}{10}

Multiplying both side by x+24

⇒ x= \frac{4(x+24)}{10}

Using distributive property of multiplication, distributing 4 with x and 24.

⇒ x= \frac{4x+96}{10}

Multiplying both side by 10

⇒ 10x= 4x+96

subtracting both side by 4x

⇒ 6x= 96

dividing both side by 6

⇒x= \frac{96}{6}

∴ x= 16

Hence, There are 16 Oak trees in the forest.

3 0
3 years ago
Julio is playing a trivia game. On his first turn, he lost 100 points. On his second turn, he lost 60 points. On his third turn,
Ivenika [448]

Answer:

-40

Step-by-step explanation:

4 0
2 years ago
Find the measure of HIW in picture.
Contact [7]
10x+2x+13=145
angle of WIJ and HIW is equal to 145 degrees
12x+13=145
12x=132
x=11
angle of WIJ is 10x
angle of HIW is 2x+13
to find angle of HIW, you plug in x=11 into 2x+13 and
the answer and angle of HIW is 35 degrees.

6 0
3 years ago
I need a step by step explanation on this problem:
miss Akunina [59]

Answer:

Dividing by 7

Step-by-step explanation:

1. Find the common term in the fraction 7

divided all by 7

4 0
2 years ago
Other questions:
  • 2/3 + -1/16= What is the fraction?
    14·1 answer
  • Given the equation 2x +4 = 4x -2, select the reasoning that correctly solves for x.
    15·2 answers
  • Which of the following shows the correct value of the square root of 175?
    7·2 answers
  • Solve the inequality
    9·1 answer
  • What is the sum of (7x-6y) and (x+y)
    11·1 answer
  • 50 pts help pls...
    11·1 answer
  • Ronda is flying her plane. She goes north for 40 miles and then heads west. She isn’t sure how far west she went, but after some
    11·2 answers
  • Answer please thanks
    13·1 answer
  • How do you find the height of a cylinder when given the surface area and the diameter?
    13·1 answer
  • Rate of change for coordinates (8,-2) (0,4) (-4,7)
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!