Question

**MEDAL/FAN
A study of five hundred adults found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 14 hours. The population standard deviation is 3 hours. What is the margin of error for a 95% confidence interval?

0.134
0.220
0.263
0.313

Answer 1

@ganeshie8
@pooja195
@Michele_Laino

Answer 2

please wait, I'm pondering...

Answer 3

Yes okay

Answer 4

a 95% confidence interval, means an error of:
\[\Large \frac{{1.96\sigma }}{{\sqrt {500} }} = \frac{{1.96 \times 3}}{{\sqrt {500} }} = ...?\]

Answer 5

I got that number: 1.96, using my tables of the "erf" function

Answer 6

N=500 is the size of your sample

Answer 7

5.88
----
22.36067977

Answer 8

yes!

Answer 9

0.2629615942

Answer 10

that's right!

Answer 11

Can u help me with this?
A coach wants to know if football players who warm up before a game will score more points than those who don't warm up. He will break the team up into two groups and make sure each player gets equal time on the field. He will then count how many points each player makes during the game. What statistic should he study?

The mean number of points earned by each player
The mean number of points earned by each group
The standard deviation of the number of points earned by each player
The standard deviation of the number of points earned by each group

Answer 12

I think the last option

Answer 13

since the coach is searching for an average value for player

Answer 14

Okay thanks!

Answer 15

Can you help me with one last question?
Crunchy Potato Chip Company has two different manufacturing plants. Company officials want to test whether each plant fills the bags with the same number of ounces. A random sample of potato chip bags from plant A had a mean of 24.2 ounces in each bag. A random sample from plant B had a mean of 22.2 ounces. They randomized the data over 100 trials and the difference of means for each trial is shown in the dot plot below. What can Crunchy Potato Chip Company conclude from this study?

Answer 16

Options:
The difference is not significant because a difference of 2.0 is very likely.
The difference is not significant because a difference of 2.0 is not very likely.
The difference is significant because a difference of 2.0 is not very likely.
The difference is significant because a difference of 2.0 is very likely.

Answer 17

I'm pondering...

Answer 18

I think the second option, since we have no outcomes whose difference is 2 ounces

Answer 19

Thank you :)

Answer 20

please wait

Answer 21

I confirm my answer

Answer 22

Okay

Answer 23

If your problem is searching for a difference 2, in absolute value, then we have to consider also the result -2.0

Answer 24

in that case the right option is option A, since outcomes for a difference about -2.0 give a low probability

Answer 25

Oh okay! Thank you very much :)

Answer 26

thanks! :)