Probability and Statistics: The mean salary offered to students who are graduating from Coastal State University this year is $24,215, with a standard deviation of 3,712. A random sample of 80 Coastal State students graduating this year has been selected. What is the probability that the mean salary offer for these 80 students is $25,000 or more?

Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.

Question

Probability and Statistics: The mean salary offered to students who are graduating from Coastal State University this year is $24,215, with a standard deviation of 3,712. A random sample of 80 Coastal State students graduating this year has been selected. What is the probability that the mean salary offer for these 80 students is $25,000 or more? 

Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.

anonymous · Answer

@amoodarya ? help

phi · Answer

you are given the population mean and the population std dev.
First step:
you need to find the sample mean (easy, it's the same as the population mean) and the sample std. dev.

anonymous · Answer

Ok. I set it up like this:
(25000-24215)/[3712/sqrt(80)]

anonymous · Answer

I really suck at statistics so I'm probably doing this wrong

phi · Answer

that gives a Z score.
we need to use it to find the prob of getting 25,000 or more.
which is the area to the right of that score.

anonymous · Answer

ok don't go anywhere

anonymous · Answer

can I use a Z table to figure it out?

phi · Answer

yes.

anonymous · Answer

wait. I'm doing something wrong. I got 1.8915 as a z-score... but isn't supposed to be 0.something?

phi · Answer

that z-score means that 25,000 is 1.89 std dev above the mean
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