Question

Mary measures the weights of five newly hatched pythons in ounces. John converts Mary’s measurements to grams. There are 28.35 grams in an ounce. Here are Mary’s results:

Python 1 2 3 4 5
Mary 1.13 oz 1.02 oz 1.23 oz 1.06 oz 1.16 oz


Show how to calculate the mean and standard deviation of John’s weights.

Answer 1

mean = (add up the weights)/5

to find the standard deviation, it's best to use a calculator (since the process is a bit tedious)

Answer 2

hi I'm here now. @jim_thompson5910

Answer 3

alright, did you manage to get anywhere with this problem?

Answer 4

Um i think that the first step would be to convert the units

Answer 5

to grams

Answer 6

so would i multiply each by 28.35 to find johns measurements in grams?

Answer 7

you are correct, what do you get when you do this?

Answer 8

i get:

Answer 9

| 32.04 | 28.92 | 34.87 | 30.1 | 32.89

Answer 10

is that right

Answer 11

it is, I'm getting this

32.0355 grams, 28.917 grams, 34.8705 grams, 30.051 grams, 32.886 grams,

but that's basically what you have (you just rounded in different places)

Answer 12

and from those i found a mean of 31.77

Answer 13

one sec

Answer 14

Ok cool

Answer 15

I'm getting

mean = 31.752

so again, you're close

Answer 16

Ok should I just keep mine?

Answer 17

You added up all the weights (in grams) and divided by 5 right?

Answer 18

yes

Answer 19

let me use your data set, one sec

Answer 20

ok so now i do the standard deviation by : (32.04-31.77)^2 + (etc.. ) for all 5 then divide by 5 right to find st deviation?

Answer 21

using your data set, I get

31.764

so it's closer

Answer 22

yes, subtract the mean from each data value, then square each difference, then add up the differences

Answer 23

ok let me do that then tell what i got

Answer 24

then you divide by 4 since you're finding the sample standard deviation most likely

Answer 25

last step is to take the square root

Answer 26

oh i divide by 4 then?

Answer 27

yes, when you're finding the sample standard deviation

Answer 28

i got .0729 + 8.1225 + 9.61 + 2.7889 + 1.2544

Answer 29

which is 21.8487.. is that right?
and how do u know if its sample or population

Answer 30

well for the most part, I think you're dealing with a sample (since you can't measure the entire population of every snake's egg), so that's why I think you're finding the sample standard deviation

Answer 31

ok

Answer 32

what about my value

Answer 33

usually in statistics, you're never going to be able to count/measure everything in the population, which is why you turn to the sample

Answer 34

let me check

Answer 35

ok!

Answer 36

i found the standard deviation to be 1.169

Answer 37

and the mean 21.8487. i rounded

Answer 38

ok just to make things clear, you're using the data set

32.04, 28.92, 34.87, 30.1, 32.89

correct?

Answer 39

yes

Answer 40

using that data set, I'm getting 2.33712002259192

Answer 41

for the mean?

Answer 42

sample standard deviation

Answer 43

oh ok
what did u get the mean to be

Answer 44

31.764

Answer 45

(32.04+28.92+34.87+30.1+32.89)/5

158.82/5

31.764

Answer 46

ok

Answer 47

did you get that? or something close to that?

Answer 48

same! so my answer would be MEAN = 31.764


; sample standard deviation = 2.33712002259192, or 2.34

Answer 49

yes, that's what I would write

Answer 50

can u check this prob for me? i already did it, i just want to see if you could check it

Answer 51

go with 2.34 since it's shorter

Answer 52

ok

Answer 53

Mary measures the weights of five newly hatched pythons in ounces. John converts Mary’s measurements to grams. There are 28.35 grams in an ounce. Here are Mary’s results:

Python 1 2 3 4 5
Mary 1.13 oz 1.02 oz 1.23 oz 1.06 oz 1.16 oz


Calculate the mean and standard deviation of Mary’s measurements using the formula for each.

Answer 54

same problem?

Answer 55

my answer: The mean of Mary's measurements is 1.12. Knowing this, we can find the standard deviation. The standard deviation would be 0.074...

sq.rt

*
(1.13 - 1.12)^2 + (1.02 - 1.12)^2 + (1.23 - 1.12)^2 + (1.06 - 1.12)^2 + (1.16 - 1.12)^2] / 5

-->.074

Answer 56

oh ok nvm

Answer 57

no, you're dividing by 4, not 5

Answer 58

oh really?

Answer 59

ok

Answer 60

then can you see if my values are all correct, that way i can just divide it by 4 so i don't have to start over

Answer 61

but my mean is right, correct? added them then divided by 5

Answer 62

yes, the mean is add them up, divide by 5

Answer 63

ok so my mean is right?

Answer 64

now for the standard deviation..

Answer 65

but why are you using Mary's measurements (in oz) when you're supposed to use John's measurements (in grams)

Answer 66

this question is different. it says to use marys

Answer 67

oh ok

Answer 68

this one says Calculate the mean and standard deviation of Mary’s measurements using the formula for each.

Answer 69

let me check

Answer 70

i gotcha

Answer 71

can u help me with finding standard deviation for this prob? i know that u divide by 4 now

Answer 72

oh and my mean is correct then right

Answer 73

your mean of 1.12 is correct

Answer 74

ok so now to find standard deviation? i try doing it on my calculator and i keep getting E's

Answer 75

can u help

Answer 76

sure, the E's mean some error is occurring, not sure what error though...

Answer 77

ok

Answer 78

i know the formula just need help solving it since my calc won't work

Answer 79

one sec

Answer 80

ok

Answer 81

You type in this

((1.13-1.12)^2+(1.02-1.12)^2+(1.23-1.12)^2+(1.06-1.12)^2+(1.16-1.12)^2)/4

to get this

0.00685

then you take the square root of that to get the final answer

0.08276472678623


So the sample standard deviation of Mary's measurements is roughly 0.08276472678623

Answer 82

thank you so much

Answer 83

np