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OpenStudy (anonymous):

PLEASE HELP!!! WILL GIVE MEDALS FAST!!! A survey found that women’s heights are normally distributed with mean 63.8 in and a standard deviation 2.3 in. A branch of the military requires women’s heights to be between 58 in and 80 in. a. Find the percentage of women meeting the height requirement. Are many women being denied the opportunity to join this branch of the military because they are too short or too tall? b. If this branch of the military changes the height requirements so that all women are eligible except the shortest 1% and the tallest 2%, what are the new height requirements.

OpenStudy (paxpolaris):

so do you use your z-table for this?

OpenStudy (anonymous):

Yes and I must show my work no idea where to start

OpenStudy (paxpolaris):

do you know how to use the z-table, ... .... to find what proportion of women have height less than 58in. ?

OpenStudy (anonymous):

Do I use the negative z score table?

OpenStudy (paxpolaris):

to get the z value you use the formula:\[\Large z= {x-\mu \over \sigma}\]

OpenStudy (anonymous):

Okay...

OpenStudy (paxpolaris):

when x=58 \[z={58-63.8 \over 2.3}\approx -2.52\]

OpenStudy (anonymous):

Okay

OpenStudy (paxpolaris):

so whats the probability at z=-2.52

OpenStudy (paxpolaris):

? what did you get in the z-table?

OpenStudy (anonymous):

.0059

OpenStudy (paxpolaris):

right ! .. so 0.59 % have height less than 58in

OpenStudy (paxpolaris):

do the same thing to find the % of women with height less than 80in.

OpenStudy (anonymous):

Ok

OpenStudy (anonymous):

7.0

OpenStudy (paxpolaris):

right .. and you won't even find that on your z-table ... lol

OpenStudy (paxpolaris):

so that means ... ?

OpenStudy (paxpolaris):

that pretty muchh 100% women have height below 80 in.

OpenStudy (paxpolaris):

so (100 - 0.59)% = 99.41% have heights between 58 and 80.

OpenStudy (anonymous):

Okay...

OpenStudy (paxpolaris):

does it make sense ... or are you still kinda lost?

OpenStudy (anonymous):

So the answer to a. Is 99.4 and b. Is 58 and 80?

OpenStudy (paxpolaris):

we just did part a. you to start fresh for part b.

OpenStudy (anonymous):

Oh ok I got it so far

OpenStudy (paxpolaris):

for the shortest 1% find the z-value that has probability closest to 0.01

OpenStudy (anonymous):

Okay...

OpenStudy (paxpolaris):

what do you get from the z-table?

OpenStudy (anonymous):

-2.33 = .0099

OpenStudy (paxpolaris):

right ... now convert z=-2.33 to x to get the height it represents

OpenStudy (anonymous):

.02277

OpenStudy (paxpolaris):

?

OpenStudy (anonymous):

.002277 + 63.8= 63.82?

OpenStudy (paxpolaris):

\[z= {x-\mu \over \sigma}\] \[\implies x= z \cdot \sigma+\mu\]

OpenStudy (paxpolaris):

-2.33*2.3+63.8

OpenStudy (anonymous):

Sorry I'm so lost :) the answer is 58.4

OpenStudy (paxpolaris):

\[\checkmark\]the same way for top 2% ... find the z where probability is closest to 0.98

OpenStudy (anonymous):

-2.34 = .0096

OpenStudy (paxpolaris):

tallest 2% means 98% are below that height ... z=0 has 0.5000 or 50% .. more than 50% is positive z

OpenStudy (anonymous):

Ok...

OpenStudy (paxpolaris):

closest to 0.9800

OpenStudy (anonymous):

-2.34 is what I've found

OpenStudy (paxpolaris):

not 0.0098 it's supposed to be 0.9800

OpenStudy (paxpolaris):

look on the positive side...

OpenStudy (anonymous):

Okay...

OpenStudy (anonymous):

2.05 = .9798

OpenStudy (paxpolaris):

right :)

OpenStudy (paxpolaris):

convert this z=2.05 to height ... and you have your answer.

OpenStudy (paxpolaris):

so what is it?

OpenStudy (anonymous):

68.5%

OpenStudy (paxpolaris):

68.5 inches :p

OpenStudy (anonymous):

So that's it?

OpenStudy (paxpolaris):

yep ... the new height requirement is you must be between 58.4 and 68.5 inches

OpenStudy (anonymous):

Okay thanks

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