Question

Check my answers please?

Answer 1

Consider the lengths of alligators to be{18.7,12.3,18.6,16.4,15.7,18.3,15.8,14.9,17.6,16.4,16.7,17.8,16.2,13.8,15.2,14.7,13.2,15.8,14.6,16.6,16.2,18.1,17.5,17.3}

according to the emperical rule, 99.7% of teh data should fall between what two numbers?

11.1 and 21.3
12.3 and 18.1
12.8 and 19.6****
13.4 and 18.8

Answer 2

99.7% is about 3 SD from the mean if that helps

Answer 3

we know what it means

Answer 4

I agree that 99.7% of your data should be within 3 standard deviations from the mean.

Use the formula for z-score to calculate the numerical value (length of alligators) that corresponds to 99.7%.

Answer 5

so can you show us how you got those two values?

Answer 6

to be honest i just guessed.. @mathmale can you show me how to do that? I am not very good at math if you can tell

Answer 7

\[z=\frac{ x-\mu }{ }\]

Answer 8

then we cannot check your answer :'(

Answer 9

ok, im lost from there

Answer 10

how do i know which values to plug in the formula?

Answer 11

When dealing with normal curves, remember the following:

68* of your data will lie within 1 s. d. of the mean;
95% within 2 s. d. , and
99.7 within 3 s. d.

Have you not used the formula before?\[z=\frac{ x-\mu }{ sigma}\]

Answer 12

Figure out what you know and what you don't
Do you have a z-score?
do you have the mean?
do you have the s.d.?

What are you looking to calculate?

Answer 13

i have used the forumula but it has been a long time.. and also im not sure, this is one of those questions where i read it and wanted to fling my book across the room.

Answer 14

should i find the median, mode range and mean of all of those nmbers? @mathmale

Answer 15

Look at the formula for z. It indicates that you must find the mean and the standard deviation from the given data.

Since we're talking about "3 s. d. from the mean," let z=3. That leaves only x to calculate. Can you take the work from here?

Answer 16

x is the mean correct?
which means i have to add all of the up and divid by the number of populations

Answer 17

@mathmale

Answer 18

\(\bar x \)

Answer 19

you're correct that it denotes simple mean

Answer 20

the mean is 16.2

Answer 21

i have to find teh SD now?

Answer 22

@mathmale

Answer 23

@nincompoop

Answer 24

you want to know the value or what is \(\mu \) ?
that is the square root of variance, the standard deviation

Answer 25

ok its 1.69 or rounded to 1.7

Answer 26

What significance does that have? Please name what you've calculated here. Is it "x"? Is it the s. d.? Is it the standard deviation?

Again, identify which of the variables in the formula for z are known and which is unknown and waiting to be calculated.\[z=\frac{ x-\mu }{ \sigma }\]

Answer 27

3 of these variables are known in this problem; you are to find the fourth.

Answer 28

he is correct the value of the standard deviation is already given from the empirical rule

Answer 29

z=3 signifies "three standard deviations above the mean."