Answer this correctly I’ll give brainalist + 10 points

Answer:

a) 0.1587 = 15.87% probability that a battery will last more than 20 hours.

b) 15.44 hours.

c) Approximately the 16th percentile.

d) 0.1974 = 19.74% probability that the lifetime of a battery is between 17.5 and 18.5.

e) 0.5704 = 57.04% probability that the mean lifetime is between 17.5 and 18.5

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

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 pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

In this question, we have that:

[tex]\mu = 18, \sigma = 2[/tex]

(a) What is the probability that a battery will last more than 20 hours?

This is 1 subtracted by the pvalue of Z when X = 20. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{20 - 18}{2}[/tex]

[tex]Z = 1[/tex]

[tex]Z = 1[/tex] has a pvalue of 0.8413

1 - 0.8413 = 0.1587

0.1587 = 15.87% probability that a battery will last more than 20 hours.

(b) Find the 10th percentile of the lifetimes.

This is X when Z has a pvalue of 0.1. So X when Z = -1.28

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]-1.28 = \frac{X - 18}{2}[/tex]

[tex]X - 18 = -1.28*2[/tex]

[tex]X = 15.44[/tex]

So 15.44 hours.

(c) A particular battery lasts 16 hours. What percentile is its lifetime on?

We have to find the pvalue of Z when X = 16. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{16 - 18}{2}[/tex]

[tex]Z = -1[/tex]

[tex]Z = -1[/tex] has a pvalue of 0.1587

Approximately the 16th percentile.

(d) What is the probability that the lifetime of a battery is between 17.5 and 18.5?

This is the pvalue of Z when X = 18.5 subtracted by the pvalue of Z when X = 17.5. So

X = 18.5

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{18.5 - 18}{2}[/tex]

[tex]Z = 0.25[/tex]

[tex]Z = 0.25[/tex] has a pvalue of 0.5987

X = 17.5

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{17.5 - 18}{2}[/tex]

[tex]Z = -0.25[/tex]

[tex]Z = -0.25[/tex] has a pvalue of 0.4013

0.5987 - 0.4013 = 0.1974

0.1974 = 19.74% probability that the lifetime of a battery is between 17.5 and 18.5.

(e) Ten batteries are chosen at random, what is the probability that the mean lifetime is between 17.5 and 18.5?

Sample of 10 means that, by the Central Limit Theorem, [tex]n = 10, s = \frac{2}{\sqrt{10}} = 0.6325[/tex]

X = 18.5

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{18.5 - 18}{0.6325}[/tex]

[tex]Z = 0.79[/tex]

[tex]Z = 0.79[/tex] has a pvalue of 0.7852

X = 17.5

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{17.5 - 18}{0.6325}[/tex]

[tex]Z = -0.79[/tex]

[tex]Z = -0.79[/tex] has a pvalue of 0.2148

0.7852 - 0.2148 = 0.5704

0.5704 = 57.04% probability that the mean lifetime is between 17.5 and 18.5

Answer:

81 samples

Step-by-step explanation:

According to the empirical rule :

Possible values of the sample mean is within 3 standard deviations of the population mean :

μ ± 3 sd(x) ; sd(x) = standard deviation of sampling distribution.

3 * sd(x) = 1

sd(x) = 1/3

Recall:

Standard deviation of sampling distribution, sd(x)

sd(x) = σ / sqrt(n)

1/3 = 3 / sqrt(n)

Square both sides

1/9 = 9/n

Cross multiply :

n * 1 = 9 * 9

n = 81

The graph has the same y Intercept as the line shown is y = 5x - 5.

A line's slope is determined by how its y coordinate changes in relation to how its x coordinate changes. y and x are the net changes in the y and x coordinates, respectively. Therefore, it is possible to write the

change in y coordinate with respect to the change in x coordinate as,

m = Δy/Δx where, m is the slope

We take two points from the graph as (-5, 0) and (0, -5)

So, the slope of line

slope = (-5 - 0)/ (0- (-5))

slope= -5 / 5

slope= -1

Using slope intercept form

y= mx+ b

y= -x+ b

Now, put x= -5 and y= 0 then

0 = -(-5)+ b

b= -5

So, the equation of line is

y= -x - 5

Here, the y intercept is -5.

So, the equation with same y intercept is

y = 5x - 5

Learn more about slope here:

https://brainly.com/question/3605446

#SPJ7

Answer:

x^3y^5 + 5x^2y^3 - 4xy^2

Step-by-step explanation:

xy^2 (x^2y^3+5xy-4)

xy^2x^2y^3 + xy^2 x 5xy - 4xy^2

xy^2x^2y^3 = yx^2y^5

xy^2 x 5xy = 5x^2y^3

x^3y^5 + 5x^2y^3 - 4xy^2

Is that what you want? Let me know.

Answer:

348

.................

Answer:

There are 1240 students at Washington middle school.  

Step-by-step explanation:

Percentages and Portions

We can find portions of a whole by correctly managing the percentages of each part. We know 25% of all students at Washington middle school were on the honor roll. From that portion, 60% of the students are seventh graders. That means 40% of the 25% are eight graders, i.e. 40*25%=10% were from eight grade.

We have 10% of all students are 124, thus the number of students are 124/10%=1240

There are 1240 students at Washington middle school.  

Let's test the answer. 25% of 1240 students are on the honor roll, which is 310 students. 40% of 310 students are from 8th grade, 40%*310 = 124 as stated in the problem

Answer: Well if you do 325 ÷ 2/5 = 130. If you try process of elimination with the numbers you’d get the right answer! Like there’s no way you could do 325 - 2/5 cause you’d get 324.6, and adding it you’d get 325.4 so your only thing left to do is multiply :)

Step-by-step explanation:

Answer:

(-4,8)

(12,0)

(4,4)

Step-by-step explanation:

graph it

Step-by-step explanation:

20a + 158+6c=you will expand the brackets

= so it is 120+60+48

20a+158+6c=120+60+48

20a+ 6c=120+60+48-158

20a+6c=70

20a divide by 20+6c divide by 6 on both side

a + c = 0.58

Answer:

When you reflect a point of the x-axis you can apply:

(x,y) -> (x,-y)

Using this:

(2,-5) -> (2,5)

Since both the x and y places are positive, it is in quadrant 1.

Hope this helps!

Step-by-step explanation:

Answer:

9

Step-by-step explanation:

7x-5+2x-1=9x-6

d/dx (9x-6)=9

Answer:

b = 4

Step-by-step explanation:

Answer:

3

Step-by-step explanation:

Answer:

5

Step-by-step explanation:

Answer:

7x - 8

Step-by-step explanation:

eight less than product of seven and X

seven and x = 7x

eight less than = - 8

put it all together = 7x - 8

Answer:

7x - 8

Step-by-step explanation:

product of seven and X

7 X x = 7x

8 less than it

7X - 8

This is because we're looking for something that is smaller than 7X by 8

Answer:

2x + 2y + 2

Step-by-step explanation:

A is right

Answer:

20

Step-by-step explanation:

given:

b=5

c=8

6(b-3)+ c

6(5-3)+8

6(2)+8

12+8

20

other method

6(b-3)+c

6b-18+8

30-18+8

12+8

20

Answer:

20

Step-by-step explanation:

b is 5 and c is 8

so we can substitute them on the given equation

Answer:

The answer is 3.4

Step-by-step explanation:

5 or more, round up

4 or less, round down

rounding 6

round up

so...

3.4

(-2, -7) and (-4, -9)

Answer:

3.4Oz

Step-by-step explanation:

Answer:

11: 1 tens, 1 ones      17: 1 tens, 7 ones     17 is greater number, it is greater by 6

Answer:

I Need Numbers Somthing....... Its Imposable to answer this

Step-by-step explanation:

Step-by-step explanation:

[tex] \tt{} \frac{24}{10} [/tex]

[tex] \tt{} \frac{24 \div 2}{10 \div 2} [/tex]

[tex]\tt{} \frac{12}{5} [/tex]

[tex]\tt{}2 \frac{2}{5} \: \: \: \: \: = 2.4[/tex]

Answer:

Step-by-step explanation:

24/300 = 0.08 = 8%

Answer:

$0.58

Step-by-step explanation:

There are 8 pencils per package. To find the value of each pencil, divide the cost by 8

4.64/8 = $0.58

Answer:

$0.58

Step-by-step explanation:

unit means one, or the rate or price of each pencil. so if the total was 4.64, youd divide 4.64 by 8, which comes out to $0.58 per pencil

Answer:

A, D

Step-by-step explanation:

It's basic math, height times length = Area.

Answer:

A and D are the only ones that i can see that would be correct

Step-by-step explanation:

Answer:

m = 5/9

Step-by-step explanation:

rise = 5

run = 9

m = rise/run

m = 5/9

Answer:

m = 5/9

Step-by-step explanation:

Use the slope formula to find the slope m.

[tex]m = \frac{5}{9}[/tex]

Answer:

i want to drive alone but i am 15 and need to be 17

Step-by-step explanation:

Answer: 10

Step-by-step explanation:

List out the numbers:

20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40

There are 10 odd numbers

Otherwise a faster method:

Odd numbers occur every other number

There are 40 - 20 = 20 numbers between 20 and 40

20/2 = 10

10 odd numbers

Answer:

22.7°

Step-by-step explanation:

22.714° to nearest 10th is 22.7

9514 1404 393

Answer:

  a ≈ 4.68

Step-by-step explanation:

The law of cosines tells you ...

  a² = b² +c² -2bc·cos(A)

  a = √(b² +c² -2bc·cos(A))

  a = √(5² +8² -2·5·8·cos(33°)) = √(25 +64 -80·0.83867) ≈ √21.906

  a ≈ 4.68

Answer:

a≈4.68

Step-by-step explanation:

have a good one!!!

We are given r(x) and c(x).

p(x) = 8x - (3x + 12)

p(x) = 8x - 3x - 12

p(x) = 5x - 12

Done.