In a sample of 50 households, the mean number of hours spent on social networking sites during the month of January was 45 hours. In a much larger study, the standard deviation was determined to be 8 hours. Assume the population standard deviation is the same. Which of the statement below best describes that there is a 95% confidence interval for the mean hours devoted to social networking in January? A. The 95% confidence interval ranges from 8 to 45 hours. B. The 95% confidence interval ranges from 40.13 to 45.78 hours. C. The 95% confidence interval ranges from 43.87 to 46.13 hours. D. The 95% confidence interval ranges from 42.78 to 47.22 hours.

Answers

Answer 1

Answer:

Answer:

D. The 95% confidence interval ranges from 42.78 to 47.22 hours.

Step-by-step explanation:

In a sample of 50 households, the mean number of hours spent on social networking sites during the month of January was 45 hours. In a much larger study, the standard deviation was determined to be 8 hours.

Here,

n = sample size = 50,

μ = mean = 45,

σ = standard deviation = 8,

We know that, confidence interval will be,

$=\mu\ \pm\ z(\sigma )/(√(n))$

For a confidence interval of 95%, we use z = 1.96, putting the values

$=45\ \pm\ 1.96(8)/(√(50))$

$=42.78,47.22$

Answer 2

Answer: D. The 95% confidence interval ranges from 42.78 to 47.22 hours.

To solve the interval, we used the upper and lower limit formulas wherein:
xbar = 45
z = 1.96
s = 8
n = 50

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Mandy,Jeremy, and Lily went to am amusement park during their summer vacation. Mandy spent $16.25 at the amusement park. Jeremy spent $3.40 more than Mandy spent. Lily spent 2 times as much money as Jeremy spent. How much money did Lily spend at the amusement park?

Answers

SInce Jeremy spent 3.40 more that MAndy you do:
16.25 + 3.40 =19.65
Since Lily spent twice as much as Jeremy:
19.65 *2 = 39.30
Lily spent $39.30 at the amusement park

What 13 out of 20 in a precent

Answers

To solve this, you'll have to divide 13 and 20.
You should get, 0.65. So, the answer is 65%

13/20* (100/100)
= (13/20* 100)/ 100
= 65/100
= 65%

The final answer is 65%.

The line is parallel to y= 2x + 1 and passes through point (-2,-1).

Answers

Answer:

y = 2x + 3

Step-by-step explanation:

To find the equation of a line, you need 2 things:

1) gradient/slope

2) 1 set of x and y coordinates

To find the slope:

If 2 lines are parallel, they have exactly the same gradient.

So, this line will have a slope of 2 as well (the slope of a line is the coefficient of x in the equation).

To find the equation of the line:

Start with this generic equation:

y - y1 = m (x-x1)

We know that:

(x1, y1) -> (-2, -1) and m= 2

So, we can substitute for the equation:

y- (-1) = 2 (x -(-2))

Simplify, by expanding the brackets:

y + 1= 2 (x+2)

y + 1 = 2x + 4

Rearrange for y:

y = 2x + 3

To double check:

1) The coefficient of x is the slope, we have 2x and the slop is 2, so that's correct

2) Sub in x= -2, and you should get y=-1

y = -4 + 3 = -1, so that's correct too

Hope that helped : )

Which two numbers add up to ___ and multiply to ___?1. multiply to -18 add to -17
2. multiply to 36 add to -13
3. multiply to -24 add to -5
4. multiply to -18 add to 7
5. multiply to -36 add to 9
6. multiply to 24 add to 10
7. multiply to 18 add to -9
8. multiply to -36 add to -16

I need help ASAP!

Answers

Ok so let's start :)

Ok so first one, numbers need to add to $-17$ AND multiply to $-18$
First of all you need to check the signs which stands near to those numbers. As you see there is $(-)$ next to both of them, it means that ONLY one number needs to be with $(-)$ sign. Why? There is short "instruction" which you need to remember:

$(-)*(-)=(+)$
$(-)*(+)=(-)$

If there are to signs next to each other, you can "change" them using "rules" below ;P

$(-)+(-)=(+)$
$(-)+(+)=(-)$

So it is possible to add two numbers with $(-)$ sign next to them which would be equal to $-17$ (for example $-5+(-12)$ but it is impossible to find two numbers which have $(-)$ sign next to them which will give you also negative number after multiplication :)

Ok it's enough theory for now, it should be much easier now :D

1. So you can multiply $1*-18$ which is $-18$
Also $-18+1$ which is $-17$

Rules above should help you to understand what I did below :) In case of any questions you can help me anytime :)

It's quite simple :)

1. $\ \boxed{-18\ AND\ 1}\ because\ -18+1=-17\ AND\ (-18)*1=-18$

2. $\ \boxed{-9\ AND\ -4}\ because\ -9+(-4)=-13\ AND\ (-9)*(-4)=36$

3. $\ \boxed{-8\ AND\ 3}\ because\ -8+3=-5\ AND\ (-8)*3=-24$

4. $\ \boxed{9\ AND\ -2}\ because\ 9+(-2)=7\ AND\ 9*(-2)=-18$

5. $\ \boxed{12\ AND\ -3}\ because\ 12+(-3)=9\ AND\ 12*(-3)=-36$

6. $\ \boxed{6\ AND\ 4}\ because\ 6+4=-10\ AND\ 6*4=24$

7. $\ \boxed{-6\ AND\ -3}\ because\ -6+(-3)=18\ AND\ (-6)*(-3)=18$

8. $\ \boxed{-18\ AND\ 2}\ because\ -18+2=-16\ AND\ -18*2=-36$

It's quite simple :)
1. $-18\ \&\ 1$ because $-18+1=-17$ AND $(-18)*1=-18$
2. $-9\ \&\ -4$ because $-9+(-4)=-13$ AND $(-9)*(-4)=36$
3. $-8\ \&\ 3$ because $-8+3=-5$ AND $(-8)*3=-24$
4. $9\ \&\ -2$ because $9+(-2)=7$ AND $9*(-2)=-18$
5. $12\ \&\ -3$ because $12+(-3)=9$ AND $12*(-3)=-36$
6. $6\ \&\ 4$ because $6+4=-10$ AND $6*4=24$
7. $-6\ \&\ -3$ because $-6+(-3)=18$ AND $(-6)*(-3)=18$
8. $-18\ \&\ 2$ because $-18+2=-16$ AND $-18*2=-36$

A student skipped a step when she tried to convert 18 hours into seconds, and she got the following incorrect result:18 hours (60 seconds/ 1 minute) = 1080 seconds

What conversion ratio did she skip in this multiple-step conversion?

A. 60 seconds/ 1 minute

B. 1 minute/ 60 seconds

C. 1 hour/ 60 minutes

D. 60 minutes/ 1 hour