Solve 2x 2 + 8x - 12 = 0 by completing the square. What are the solutions?

The amount of money spent on textbooks per year for students is approximately normal.

Ostrovityanka [42]

Answer:a

a

$336.04 < \mu < 443.96$

b

The margin of error will increase

c

The margin of error will decreases

d

The 99% confidence interval is $0.4107 < p < 0.4293$

Step-by-step explanation:

From the question we are told that

The sample size $n = 19$

The sample mean is $\= x = \$\ 390$

The standard deviation is $\sigma = \$ \ 120$

Given that the confidence level is 95% then the level of significance is mathematically represented as

$\alpha = 100 - 95$

$\alpha = 5 \%$

$\alpha = 0.05$

Next we obtain the critical value of $\frac{\alpha }{2}$ from the normal distribution table

So

$Z_{\frac{\alpha }{2} } = 1.96$

The margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} } * \frac{\sigma}{\sqrt{n} }$

=> $E = 1.96 * \frac{120}{\sqrt{19} }$

=> $E = 53.96$

The 95% confidence interval is

$\= x - E < \mu < \= x + E$

=> $390 - 53.96 < \mu < 390 - 53.96$

=> $336.04 < \mu < 443.96$

When the confidence level increases the $Z_{\frac{\alpha }{2} }$ also increases which increases the margin of error hence the confidence level becomes wider

Generally the sample size mathematically varies with margin of error as follows

$n \ \ \alpha \ \ \frac{1}{E^2 }$

So if the sample size increases the margin of error decrease

The sample proportion is mathematically represented as

$\r p = \frac{210}{500}$

$\r p = 0.42$

Given that the confidence level is 0.99 the level of significance is $\alpha = 0.01$

The critical value of $\frac{\alpha }{2}$ from the normal distribution table is

$Z_{\frac{\alpha }{2} } = 2.58$

Generally the margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} }* \sqrt{ \frac{\r p (1- \r p )}{n} }$

=> $E = 0.42 * \sqrt{ \frac{0.42 (1- 0.42 )}{ 500} }$

=> $E = 0.0093$

The 99% confidence interval is

$\r p - E < p < \r p + E$

$0.42 - 0.0093 < p < 0.42 + 0.0093$

$0.4107 < p < 0.4293$

4 0

3 years ago

Is it true that the planes x + 2y − 2z = 7 and x + 2y − 2z = −5 are two units away from the plane x + 2y − 2z = 1?

zhuklara [117]

Lets Find It Out..

First we'll find the equation of ALL planes parallel to the original one.

As a model consider this lesson:

Equation of a plane parallel to other

The normal vector is:
→n=<1,2−2>

The equation of the plane parallel to the original one passing through P(x0,y0,z0)is:

→n⋅< x−x0,y−y0,z−z0>=0
<1,2,−2>⋅<x−x0,y−y0,z−z0>=0
x−x0+2y−2y0−2z+2z0=0
x+2y−2z−x0−2y0+2z0=0

Or

x+2y−2z+d=0 [1]
where a=1, b=2, c=−2 and d=−x0−2y0+2z0

Now we'll find planes that obey the previous formula and at a distance of 2 units from a point in the original plane. (We should expect 2 results, one for each half-space delimited by the original plane.)
As a model consider this lesson:

Distance between 2 parallel planes

In the original plane let's choose a point.
For instance, when x=0 and y=0:
x+2y−2z=1 => 0+2⋅0−2z=1 => z=−12
→P1(0,0,−12)

In the formula of the distance between a point and a plane (not any plane but a plane parallel to the original one, equation [1] ), keeping D=2, and d as d itself, we get:

D=|ax1+by1+cz1+d|√a2+b2+c2
2=∣∣1⋅0+2⋅0+(−2)⋅(−12)+d∣∣√1+4+4
|d+1|=2⋅3 => |d+1|=6First solution:
d+1=6 => d=5
→x+2y−2z+5=0Second solution:
d+1=−6 => d=−7
→x+2y−2z−7=0

8 0

3 years ago

A certain antihistamine is often prescribed for allergies. A typical dose for a 100-pound person is 25 mg every six hours. Comp

koban [17]

Given that a certain antihistamine is often prescribed for allergies.

And typical dose for 100-pound person is 25 mg every 6 hours.

a) Let us calculate dose per 1 hour for 100-pound person= $\frac{25}{6} mg/hr$

Since 1 week means 7X24= 168 hours, dosage per 1 week = dosage per 168 hours

$=168X\frac{25}{6} = 700mg$

The number of 12.8 chew able tablets would be taken in a week= $\frac{700}{12.8}=54.6875$

Hence number of 12.8mg chew able tablets would be taken in a week is 55.

b) Now we can use earlier answer for this problem, since 12.8mg tablet is replaced with 9ml liquid, 55 bottles of 9ml liquid are to be taken in a week.

Hence amount of liquid histamine should a 100-pound person take in a week = 55X9

=495ml

3 0

3 years ago

Pls help will mark brainliest

yanalaym [24]

Answer:

1.93433

Step-by-step explanation:

Since all triangles have an interior angle sum of 180, the second angle is 45. this also means that x and y are equal. Using the pythagorean theorem, we can produce the equation $2\sqrt{14} = 2x^2$ . dividing both sides by two we get $x^2= \sqrt{14}$ . when we take the square root of root 14 we get 1.934335

4 0

3 years ago

Help me with this equation:tan36=48/14

Zigmanuir [339]

It's difficult to spot what kind of help is needed.

There's no variable in that equation whose value needs to be found.

It appears to be simply a statement, saying that the tangent of 36 degrees
is (3 and 3/7) .

As such, it's false, since the tangent of 36 degrees is roughly 0.7265 .

What exactly is the question ?

5 0

3 years ago