Which expression or value is equivalent to (−3+5i)(−3−5i)?

A researcher examines 27 sedimentary samples for bromide concentration. The mean bromide concentration for the sample data is 0.

FrozenT [24]

Answer:

Critical value: $z = 1.645$

The 90% confidence interval for the population mean bromide concentration is (0.376, 0.39).

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$ . This value of z is the critical value

Now, find M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

$M = 1.645*\frac{0.0209}{\sqrt{27}} = 0.0066$

The lower end of the interval is the mean subtracted by M. So it is 0.383 - 0.0066 = 0.376 cc/cubic meter

The upper end of the interval is the mean added to M. So it is 0.383 + 0.0066 = 0.39 cc/cubic meter

The 90% confidence interval for the population mean bromide concentration is (0.376, 0.39).

6 0

3 years ago

Brandy set her watch 4 seconds behind and it falls behind another 1 second every day. How many days had it been since brandy las

kari74 [83]

Answer:

18 days

Step-by-step explanation:

Let x represent number of days.

We have been given that Brandy's watch falls 1 second every day. So Brandy's watch will fall $1x$ seconds behind in x days.

We are also told that Brandy set her watch 4 seconds behind, so Brady's watch will be behind by total $x+4$ seconds in x days.

Since Brady's watch is 22 seconds behind, so we will equate $x+4$ by 22 to solve for x as:

$x+4=22$

$x+4-4=22-4$

$x=18$

Therefore, Brandy set her watch 18 days ago.

5 0

3 years ago

Read 2 more answers

Whats the unit rate 140 mi in 3.5 h

Furkat [3]

40 miles per hour because 140 divided by 3.5 is 40.

8 0

3 years ago

Read 2 more answers

Choose the student with the correct answer. Pls Help ;-;

Dafna11 [192]

Answer:

Frida

Step-by-step explanation:

y = 1000(2)^x

Mrs. Smith is saying that the number of termites will double each week, and Mr. Smith is saying that the number of termites will increase by 100% each week.

Let's just look at (2)^x. If we substitute numbers for x, we get:

x = 1 ⇒ 2
x = 2 ⇒ 4
x = 3 ⇒ 8
x = 4 ⇒ 16
x = 5 ⇒ 32
x = 6 ⇒ 64
x = 7 ⇒ 128

We can see that the output number doubles by 2, or in other words, increases by 100% of its value.

Therefore, Frida is correct in thinking that both Mr. and Mrs. Smith's interpretations are correct.

6 0

2 years ago

What is the equation of a circle with center of (4,2) passing through the point (7,2)

attashe74 [19]

Answer:

(x-4)^2 + (y-2)^2 = 3^2

or

(x-4)^2 + (y-2)^2 = 9 (simplified if needed)

Step-by-step explanation:

-Equation of a circle is:

$(x-h)^2+(y-k)^2=r^2$ where the center is (h, k) and the radius is $r^2$ .

-Place the center and the point onto that equation:

$(7-4)^2+(2-2)^2=r^2$

-Then, you solve:

$(7-4)^2+(2-2)^2=r^2$

$(3)^2+(0)^2=r^2$

$9 +0=r^2$

$9=r^2$

$\sqrt{9} =\sqrt{r^2}$

$3=r$

-So, the result is:

$(x-4)^2+(y-2)^2=3^2$

or

$(x-4)^2+(y-2)^2=9$ (simplified if needed)

3 0

3 years ago