The Z-score is calculated by the formula below

Step 2: Substitute the given parameters in the formula

Hence, the z-score of a person who scored 145 on the exam is -0.5
Elena packed 48 cubes.
Each cube has an edge of 1 centimeter.
The number of layers that Elena can make depends on how each layer is arranged and depends on how many cubes are there in a layer.
Assume that each layer has only 1 cube, then there are 48 layers.
7.81 then 7.14 then 7.081 then 7.002