@precal

Question

@precal

aihberkhan · Answer

A laboratory weighs filters from a coal mine to measure the amount of dust in the mine atmosphere. Repeated measurements of the weight of dust on the same filter vary normally with a standard deviation of 0:08 milligram (mg) because the weighing is not perfectly precise. The dust on a particular filter actually weighs 123 mg. Repeated weighings will then have the normal distribution with mean 123 mg and standard deviation 0.08 mg.

What is the probability that the laboratory reports a weight of 124 mg or higher for this filter (the one that was weighed 3 times)?

precal · Answer

Sorry, I haven't done stats in a long time.

aihberkhan · Answer

Its okay :) @precal

aihberkhan · Answer

@Mehek14 

@xapproachesinfinity

aihberkhan · Answer

Please help...

aihberkhan · Answer

@zepdrix

zepdrix · Answer

standard deviation?
Ooo sorry I don't know this shenanigans :((

aihberkhan · Answer

Aw okay @zepdrix

precal · Answer

Have you tried to see if Khan Academy has anything in STATS

aihberkhan · Answer

Yes, but even if I know the concept I still can't seem to find the answer..

aihberkhan · Answer

@Astrophysics

aihberkhan · Answer

@mathmale

precal · Answer

https://www.easycalculation.com/statistics/standard-deviation.php

precal · Answer

How about this standard deviation calculator?  How about wolfram alpha?

aihberkhan · Answer

Okay ill try :)

aihberkhan · Answer

I am just really confused..

zepdrix · Answer

lol they have a love calculator on the same site :D

mathmale · Answer

I could help you part of the way, but do not understand how to take into account the fact that this particular filter was weighed three times.

You are told that the mean filter weight is 123 mg, and that the s. d. is 0.08 mg.  You are asked what the probability is that the filter will weigh in at 124 mg or greater.

mathmale · Answer

Since 124 mg is just 1 mg greater than the mean (123 mg), the probability in question will be just greater than 0.5.

You'll need to find the z-score for that 124 mg, taking into account the given mean (123 mg) and given s. d. (0.08 mg).

Have you calculated z scores before?

mathmale · Answer

OpenStudy tells me you're now "offline."

aihberkhan · Answer

Hi! Sorry that day, since no one was replying I left. But I would like to ask, can we continue? I have calculated z scores before but still am not that familiar with it.

@mathmale