Question

HELP PLEASE!!
Susan keeps track of the number of tickets sold for each play presented at the community theater. within how many standard deviations of the mean do all the values fall?
135, 71, 69, 80, 158, 152, 161, 96, 122, 118, 87, 85.

Answer 1

First you need to find the mean (the average)
Do you know how to do that ?

Answer 2

yeah the mean=111.16

Answer 3

I think

Answer 4

read this....
http://www.mathsisfun.com/data/standard-deviation.html

Answer 5

so the mean is wrong

Answer 6

135 + 71 + 69 + 80 + 158 + 152 + 161 + 96 + 122 + 118 + 87 + 85 =
1334. Now take 1334 and divide it by the total # of numbers, which is 12.
1334/12 = 111.166 rounds to 111.17

Now take each numbers difference from the mean and square it.
135 - 111.17 = 23.83
71 - 111.17 = - 40.17
69 - 111.17 = -42.17
80 - 111.17 = -31.17
158 - 111.17 = 46.83
152 - 111.17 = 40.83
161 - 111.17 = 49.83
96 - 111.17 = - 15.17
122 - 111.17 = 10.83
118 - 111.17 = 6.83
87 - 111.17 = - 24.17
85 - 111.17 = - 26.17

28.83^2 + (-40.17)^2 + (-42.17)^2 + (-31.17)^2 + 46.83^2 + 40.83^2 + 49.83^2 + (-15.17)^2 + 10.83^2 + 6.83^2 + (-24.17)^2 + (-26.17)^2 = 831.17 + 1613.63 + 1778.31 + 971.57 + 2193.05 + 1667.09 + 2483.03 + 230.13 + 117.29 + 46.65 + 584.19 + 684.87 =
13200.98. now take 13200.98 and divide it by 12 = 1100.08 (this is your variance)
The standard deviation is the square root of your variance.
sq rt of 1100.08 = 33.17

I am going to say the standard deviation is 33.17. If I added all of this correctly. You might want to get another opinion.

Answer 7

@Opcode ....can you tell me if I did this correctly. I am not asking you to do the math, just tell me if I set it up right

Answer 8

for answers I have 3, 4, 5, 2 so the answer's 3??

Answer 9

oh...I must have messed up big time....I don't know....let me get somebody here to help

Answer 10

@Luis_Rivera ....I must have messed up big time on this...can you help

Answer 11

@Preetha ....can you help

Answer 12

@jim_thompson5910 ......I think I messed up here....pretty sure I did...can you help

Answer 13

@satellite73 ....I really messed up on this one....can you help fix it ?

Answer 14

@saifoo.khan ....please help

Answer 15

@Chooch146 ....I messed up here, can you help me fix it ?

Answer 16

what are your choices?

Answer 17

work looks right, answer is here
http://www.wolframalpha.com/input/?i=standard+deviation+ {135%2C+71%2C+69%2C+80%2C+158%2C+152%2C+161%2C+96%2C+122%2C+118%2C+87%2C+85.}

Answer 18

2,3,4,5.....that is what nicole said the answer choices were

Answer 19

looks like sd is 34.3

Answer 20

Its d within two standard deviations. When you calculate standard deviation for those number you get 36.35 and the mean is 116.1. all of those numbers are contained within 116.1 +or - 2(36.35)

Answer 21

So the answer is 2 ?

Answer 22

um yup!

Answer 23

thank you......you are a miracle worker

Answer 24

aw lolol thanks:P

Answer 25

@nicole-0109 .....Chooch got the answer....it is 2

Answer 26

thank you so much to all

Answer 27

:P