What is a physical or mental representation of an object or an event

The density of gold is 19.3g/cm3. what is the volume of a 13 g gold nugget? ( density: d= m/v)

Aresearcher plans to conduct a test of hypotheses at the 1% significance level. she designs her study to have a power of 0.90 at a particular alternative value of the parameter of interest. the probability that the researcher will commit a type ii error for the particular alternative value of the parameter at which she computed the power is: a. 0.90. b. 0.01. c. 0.10. d. equal to 1

A10.0 kg cart and a 15kg cart are locked together with a compressed spring between them. they are then released so that the spring pushes the two carts apart. the 10.0 kg cart is moving at 4.5 m/s afterward. how fast is the 15kg cart moving? 3.0 m/s 2.0 m/s 4.5 m/s 5.0 m/s