The quotient of a number and negative 5 decreased by 9 is 2

J.J.Bean sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet.

melamori03 [73]

Answer:

99% confidence interval for the true mean difference between the mean amount of mail-order purchases and the mean amount of internet purchases is [$(-31.82) , $12.02].

Step-by-step explanation:

We are given that a random sample of 16 sales receipts for mail-order sales results in a mean sale amount of $74.50 with a standard deviation of $17.25.

A random sample of 9 sales receipts for internet sales results in a mean sale amount of $84.40 with a standard deviation of $21.25.

The pivotal quantity that will be used for constructing 99% confidence interval for true mean difference is given by;

P.Q. = $\frac{(\bar X_1-\bar X_2)-(\mu_1-\mu_2)}{s_p \times \sqrt{\frac{1}{n_1}+\frac{1}{n_2} } }$ ~ $t__n_1_+_n_2_-_2$

where, $\bar X_1$ = sample mean for mail-order sales = $74.50

$\bar X_2$ = sample mean for internet sales = $84.40

$s_1$ = sample standard deviation for mail-order purchases = $17.25

$s_2$ = sample standard deviation for internet purchases = $21.25

$n_1$ = sample of sales receipts for mail-order purchases = 16

$n_2$ = sample of sales receipts for internet purchases = 9

Also, $s_p =\sqrt{\frac{(n_1-1)\times s_1^{2}+(n_2-1)\times s_2^{2} }{n_1+n_2-2} }$ = $\sqrt{\frac{(16-1)\times 17.25^{2}+(9-1)\times 21.25^{2} }{16+9-2} }$ = 18.74

The true mean difference between the mean amount of mail-order purchases and the mean amount of internet purchases is represented by ( $\mu_1-\mu_2$ ).

Now, 99% confidence interval for ( $\mu_1-\mu_2$ ) is given by;

= $(\bar X_1-\bar X_2) \pm t_(_\frac{\alpha}{2}_) \times s_p \times \sqrt{\frac{1}{n_1} +\frac{1}{n_2}}$

Here, the critical value of t at 0.5% level of significance and 23 degrees of freedom is given as 2.807.

= $(74.50-84.40) \pm (2.807 \times 18.74 \times \sqrt{\frac{1}{16} +\frac{1}{9}})$

= [$-31.82 , $12.02]

Hence, 99% confidence interval for the true mean difference between the mean amount of mail-order purchases and the mean amount of internet purchases is [$(-31.82) , $12.02].

5 0

3 years ago

Which is equivalent

arlik [135]

Answer:

D 8√(10) ^3x

Step-by-step explanation:

We have

sqrt(10) ^ (3/4x)

We can rewrite the sqrt as ^1/2

10 ^ (1/2) ^ (3/4x)

We know that a^b^c = a^(b*c)

10 ^(1/2 *3/4x)

10 ^(3/8 x)

The numerator is the power

The denominator is the root

8√(10) ^3x

8 0

3 years ago

Find an equation of the sphere with center (2, −10, 3) and radius 5. $$25=(x−2)2+(y−(−10))2+(z−3)2 use an equation to describe i

lana66690 [7]

In the $x,y$ plane, we have $z=0$ everywhere. So in the equation of the sphere, we have

$25=(x-2)^2+(y+10)^2+(-3)^2\implies(x-2)^2+(y+10)^2=16=4^2$

which is a circle centered at (2, -10, 0) of radius 4.

In the $x,z$ plane, we have $y=0$ , which gives

$25=(x-2)^2+10^2+(z-3)^2\implies(x-2)^2+(z-3)^2=-75$

But any squared real quantity is positive, so there is no intersection between the sphere and this plane.

In the $y,z$ plane, $x=0$ , so

$25=(-2)^2+(y+10)^2+(z-3)^2\implies(y+10)^2+(z-3)^2=21=(\sqrt{21})^2$

which is a circle centered at (0, -10, 3) of radius $\sqrt{21}$ .

3 0

3 years ago

You are building a tower that is 4 ft. tall. Which would your need more of to build your 4 ft. tall tower?

laiz [17]

Answer:

pennies

Step-by-step explanation:

because they are thinner than notebooks and you will need more of them

3 0

2 years ago

CAN SOME ONE PLS HELP ME THIS IS REALLY HARD

Dmitry_Shevchenko [17]

Answer: 1.25 times as far

Step-by-step explanation:

This problem requires you to find something called the unit rate.

Getting the unit rate for Car A is very simple, and can be found to be 25mi/gal.

To find the unit rate for Car B, simply look at the second row. Because the car can go 60 miles on 3 gallons of gas, divide both these numbers by 3 to get 20mi/gal.

Then, simply multiply both of these numbers by 11 to get 25 * 11 = 275, and 20 * 11 = 220.

Then, by doing 275/220, you get your answer: 1.25.

Hope it helps :) and let me know if you want me to elaborate.

4 0

2 years ago

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