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Optional: Pls explain dark matter to me

yay

Step-by-step explanation:

Dark matter is a form of matter thought to account for approximately 85% of the matter in the universe and about a quarter of its total mass–energy density or about 2.241×10⁻²⁷ kg/m³.

Also may be said as,

Nonluminous material that is postulated to exist in space and that could take any of several forms including weakly interacting particles  or high-energy randomly moving particles created soon after the Big Bang.

Step-by-step explanation:

- The Z-score allows you to decide if your sample is different from the population mean. In order to use z, you must know four things:

- Usually in stats, you don’t know anything about a population, so instead of a Z score you use a T-Test with a T Statistic.

- The major difference between using a Z score and a T statistic is that you have to estimate the population standard deviation. The T test is also used if you have a small sample size (less than 30).