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2 years ago

What do i say for this please help :((((

Mathematics

1 answer:

Ostrovityanka [42]2 years ago

3 0

Answer:

Step-by-step explanation:

Error 1) It should be divided by 5.

x - 5 = 0

x = 5

Error 2) -3 15 0 -1 5

coefficient of x² is 0 and it is not included

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A simple random sample of size n is drawn from a population that is normally distributed. The sample mean, x overbar, is found

joja [24]

Answer:

(a) 80% confidence interval for the population mean is [109.24 , 116.76].

(b) 80% confidence interval for the population mean is [109.86 , 116.14].

(c) 98% confidence interval for the population mean is [105.56 , 120.44].

(d) No, we could not have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed.

Step-by-step explanation:

We are given that a simple random sample of size n is drawn from a population that is normally distributed.

The sample mean is found to be 113 and the sample standard deviation is found to be 10.

(a) The sample size given is n = 13.

Firstly, the pivotal quantity for 80% confidence interval for the population mean is given by;

P.Q. = $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample mean = 113

s = sample standard deviation = 10

n = sample size = 13

$\mu$ = population mean

Here for constructing 80% confidence interval we have used One-sample t test statistics as we don't know about population standard deviation.

So, 80% confidence interval for the population mean, $\mu$ is ;

P(-1.356 < $t_1_2$ < 1.356) = 0.80 {As the critical value of t at 12 degree

of freedom are -1.356 & 1.356 with P = 10%}

P(-1.356 < $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ < 1.356) = 0.80

P( $-1.356 \times }{\frac{s}{\sqrt{n} } }$ < ${\bar X-\mu}$ < $1.356 \times }{\frac{s}{\sqrt{n} } }$ ) = 0.80

P( $\bar X-1.356 \times }{\frac{s}{\sqrt{n} } }$ < $\mu$ < $\bar X+1.356 \times }{\frac{s}{\sqrt{n} } }$ ) = 0.80

80% confidence interval for $\mu$ = [ $\bar X-1.356 \times }{\frac{s}{\sqrt{n} } }$ , $\bar X+1.356 \times }{\frac{s}{\sqrt{n} } }$ ]

= [ $113-1.356 \times }{\frac{10}{\sqrt{13} } }$ , $113+1.356 \times }{\frac{10}{\sqrt{13} } }$ ]

= [109.24 , 116.76]

Therefore, 80% confidence interval for the population mean is [109.24 , 116.76].

(b) Now, the sample size has been changed to 18, i.e; n = 18.

So, the critical values of t at 17 degree of freedom would now be -1.333 & 1.333 with P = 10%.

80% confidence interval for $\mu$ = [ $\bar X-1.333 \times }{\frac{s}{\sqrt{n} } }$ , $\bar X+1.333 \times }{\frac{s}{\sqrt{n} } }$ ]

= [ $113-1.333 \times }{\frac{10}{\sqrt{18} } }$ , $113+1.333 \times }{\frac{10}{\sqrt{18} } }$ ]

= [109.86 , 116.14]

Therefore, 80% confidence interval for the population mean is [109.86 , 116.14].

(c) Now, we have to construct 98% confidence interval with sample size, n = 13.

So, the critical values of t at 12 degree of freedom would now be -2.681 & 2.681 with P = 1%.

98% confidence interval for $\mu$ = [ $\bar X-2.681 \times }{\frac{s}{\sqrt{n} } }$ , $\bar X+2.681 \times }{\frac{s}{\sqrt{n} } }$ ]

= [ $113-2.681 \times }{\frac{10}{\sqrt{13} } }$ , $113+2.681 \times }{\frac{10}{\sqrt{13} } }$ ]

= [105.56 , 120.44]

Therefore, 98% confidence interval for the population mean is [105.56 , 120.44].

(d) No, we could not have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed because t test statistics is used only when the data follows normal distribution.

6 0

2 years ago

This Christmas, your brother Jack will be 2 years from being twice as old as your sister Jen. The sum of Jacks age and three tim

zhannawk [14.2K]

Age of Jen is 13.6 years old

Solution:

Let "x" be the age of Jack and "y" be the age of Jen

Given that This Christmas, your brother Jack will be 2 years from being twice as old as your sister Jen

The above sentence can be written mathematically as:

Jack age + 2 = twice of age of Jen

$x + 2 = 2y\\\\x = 2y - 2---- eqn 1$

The sum of Jacks age and three times Jen's age is 66

Jack age + three times Jen age = 66

x + 3y = 66 ---- eqn 2

Substitute eqn 1 in eqn 2

2y - 2 + 3y = 66

5y - 2 = 66

5y = 68

Thus age of Jen is 13.6 years old

5 0

3 years ago

What is the surface area of the triangular prism?

Natalija [7]

Answer:

the answer is c

Step-by-step explanation:

7 0

2 years ago

Lisa sells cars for a salary of 2500 per month plus 2% commission of her total car sales. What should her total of car sales be

Bumek [7]

Answer:

$50,000

Step-by-step explanation:

Let x = car sales

We multiply x by 0.02 since she earns 2% along with the added $2500 so that she can end up with $3500

3500 = 0.02x + 2500

Subtract 2500 from both sides

3500 - 2500 = 0.02x + 2500 - 2500

1000 = 0.02x

Divide both sides by 0.02

1000/0.02 = 0.02x/0.02

x = 50000

3 0

2 years ago

He graph shows the distance Henry drives on a trip. What is Henry’s speed

tatyana61 [14]

60 mph would be the correct answer!
Brainilest please! :)

8 0

3 years ago

Read 2 more answers