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Me what is the value of x? showing work would be appreciated - ! : )

The mean of a set of data is -3.82 and its standard deviation is 2.31. find the z score for a value of 3.99.

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?