Descriptive Statistics and the Normal Distribution:

I am really lost with my psychology statistics class and couldn't understand how to get to the answer to those questions. Hope you could help me with this.

Assume that the length of gecko lizards are normally distributed with a mean of 5.8" and standard deviation of .22".

QUESTION: If normal length for geckos is defined as the middle 80% of the distribution, what is the longest and shortest a gecko could be and still be considered "of normal length"? (I need support with the steps to arrive to the answer too)

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You and your friends (a total group of 10) are avid videogame players putting many hours into playing videogames every day. One day you decided to find out if this is normal behavior. You calculate that on average you and your friends play 23 hours of videogames a week. Upon researching, you discover that in the United States, the average person plays 17.5 hours of videogames a week with a standard deviation of 5.5 hours.

QUESTION: Compute the z test for this situation ( I need support with the steps to arrive to the answer too)