No idea how to do this shit. Friend needs help:/

No idea how to do this shit. Friend needs help:/

What do you study?

>30 parties over a weekend of work

tips equal zero for being a lazy cunt.

I don't study anything but my friend needed help with this statistic problem

Use a calculator

nigga use your ti 84
2nd vars ->2
also pay attention in class
also i dont think that this is the place to post that

Do I have to help? It's like 2 o'clock in the morning and I cba.

Math fucking sucks, but maybe some arrogant ass STEM fag can help you. "Oh look at me I'm an engineer and programmer, I make millions every year and I'm superior to everyone else around me!"

Everyone looks at Math as a competition, like always trying to one-up the other person. Oh you took high level calculus? Well I took number theory, group theory, complex analysis, and linear algebra. I mean, what's the fucking point? Why brag about it? Who cares what level of Math you studied in school? Who cares if you took brain-crushing Math courses? Is your self-esteem that low? Are you that insecure?

I took remedial math in College, and flunked it 3 times. Still ended up graduating, and didn't have a problem with it. Only STEM fags really give a shit about what level of Math they took, most people I know think Math is fucking retarded.

side note i forget whether the 30 really matters
im sure it does but i forget how

what the fuck is wrong with you
just look this shit up youre on the internet
this is shitposting x100

I can't find it:/

Know what a z table is?

Usually how I do these problems is visualize it like a graph. The answer to a is the region of the graph to the right of 300$. That is you get the entire probability of that region, since it's "at least."

But that's only half of the question. It wants to know the probability of the total being 300$, which is the same as asking for the probability of the mean tip being 10$ at least thirty times.

Which is kind of complicated so just plug in to the z formula with 30 -1 as df and 10$ as the variable.

no idea how to screenshot either apparently

do you have a textbook?

Fucking MyStatLab
Kek

>Math is retarded
Math is used in absolutely everything, retard.

You are just projecting because you are not capable of computing basic math problems. Although there is nothing wrong with that, to brush it off as it being "stupid", is a shitty cop out for failure.

cont.

you will need:

z table (just google it)

z = (10$ - 8.70 )/ 4.4

shit this is even easier than i thought

...

about .3859

Ok, so from what I can gather you need the probability of the distribution (I'm assuming it's normal I'll get to the skew later) being above the average amount of money required be be earned for each tip 30 times. This average amount is $10. Now the Z value for a normal distribution (taken from wiki) is the "distance between the raw score and the population mean in units of the standard deviation." It's been a while since I've done this so apologies if i am wrong. The difference between the mean and required average is $1.30 now to get this into unit of the standard deviation you must divide it by the standard deviation so $1.30/$4.40 giving you 0.29545. You then need to go to the standard normal table to see what the probability of getting a value lower than this 0.29545. since the distribution is slightly skewed to the right I'm going to round it to 0.3 and on the Z table this gives you 0.61791 as a probability. Since this is the probability of getting less than $10 you need to do 1-0.61791 giving you a probability of getting $10 or more once as 0.38209. I originally thought you'd have to do this to the power of thirty to account for the 30x you'd need to get this but when doing that you get 2.917x10^-13 so I'm at my wits end at this point. If i remember how to do it I'll update but hopefully this got you somewhere :)

Value lower than this $10 average** sorry

Values of 0.3859 and 0.38209 are close enough to give them a try to see what happens.

> I originally thought you'd have to do this to the power of thirty to account for the 30x

I think that is already accounted for in the std dev and mean, like you can't even get those numbers without the n value. Besides, since n is greater than 26, the central limit theorem applies, and all your expected probabilities hold forever, so a 38% probability at 30 df is the same as 30% at 1000000 df.

>a 38% is the same as a 38%

fixed lol

>most people I know think Math is fucking retarded.

They're called retards

>
Ah I see. Thank you for clearing that up. Haven't done any stats since first year.

Z scores dumbass

Haven't read any of the thread, but here's the answer:

Y = X1 + X2 + ... + X30
E(Y) = 30*E(X) = 261
Var(Y) = 30*Var(X) = 30*4,4^2 = 580.8

Pr(Y>300) = 1 - Pr(Y