Question

1) A company manufactures batteries having lifespans that are normally distributed, with a mean of 45 mo and a standard deviation of 5 mo. Find the probability that a battery chosen at random will have a lifespan of 50-55 mo.

2) According to a national survey, 16% of U.S. adults use the Internet to make telephone calls. In a random survey of 100 adults, what is the probability that at most 20 of them use the internet to make telelphone calls?

I have another question but it doesn't fit message me please I need these fast

Answer 1

do you have a ti83?

Answer 2

ti84

Answer 3

then its pretty simple to input these. stats button has them

Answer 4

I am not sure how to I don't use it much I use paper a majority of the time.

Answer 5

normalCDF(low,high, mean, sd)

Answer 6

I don't see those on the calculator do you think you could do them for me I am in such a hurry my license is on the line if I don't get these done. I would super appreciate it

Answer 7

2nd, VARS, pick normalCDF and input the information

Answer 8

do not ask me to break the rules of a site that i moderate .... thats just crass

Answer 9

What do all of these mean though? and these aren't for a test these are a practice sheet that my dad gave me and I don't know how to do them

Answer 10

you have the calculator?

Answer 11

Yes I do I just don't know where to put the information in

Answer 12

you cant do these 'by hand' unless you want to integrate a rather ugly looking function

Answer 13

you need table or calculator .. or learn integration

Answer 14

Can you walk me through the first one because I don't know where to plug the information in

Answer 15

if you have the calculator, then yes ... do youhave it? is it on?

Answer 16

Yes I have it right now and I went to the normalcdf

Answer 17

then the function requires 4 inputs

normalCDF(low, high, mean, sd)

all of these are stated in the information, can you define them for me?

Answer 18

low 50, high 55, mean 45, and sd 5 right?

Answer 19

very good, remember to use the 'comma' button to seperate the inputs.

Answer 20

ok so for lower i put 50 for upper i put 55 for the u thing i put 45 and the o thing i put 5?

Answer 21

correct

Answer 22

Then I hit enter? or paste?

Answer 23

enter

Answer 24

It gave me .1359051975

Answer 25

good the wolf gives the same thing

http://www.wolframalpha.com/input/?i=normalcdf%2850%2C55%2C45%2C5%29

round to 4 decies is the usual

.1359

Answer 26

and then that is the probability that it will happen?

Answer 27

yes

Answer 28

Ok is it different for the second one because it has a percentage?

Answer 29

the second one is similar, but the distribution is Poisson, not Normal different function

Answer 30

So i would do it differently in the calculator?

Answer 31

you would choose a different distribution yes, and input its required values

Answer 32

So in the menu I would choose poissoncdf or pdf

Answer 33

C stands for the sum of stuff, cumulative.

P stands for point ... not very useful

and im rethinking: the binomailCDF function is prolly better suited

Answer 34

Ok thanks I really appreciate it

Answer 35

lets read that second one carefully, i tend to read too fast

16% of U.S. adults use the Internet to make telephone calls.
proportion or mean = .16

In a random survey of 100 adults
n=100


what is the probability that at most 20 of them use the internet to make telelphone calls?

cumulative sum of 0 to 20

binomialCDF sounds good to me.

so: binomCDF(n,mean,max)

Answer 36

Hey sorry I had to go pick up my sister @amistre64

Answer 37

did u ever get the answers? and work?