Question

The percentage of all possible observations of the variable that lie between 7 & 12 equals the area under its density curve between _ and _, expressed as a percentage.

Short answer

Percentage of total observations that lie between 7 & 12 equals the area under density curve between x > 7 & x <10 expressed as a percentage

Step-by-step solution

Density Curve Concept 

Density Curve is a graphical representation of numerical distribution, having variable outcomes that are continuous (which can take non whole values), like weight = 45.3 Kgs

Density Curve Probability 

It shows likelihood ( probability) of continuous variable' outcomes. As total probability = 1, total area under the curve is also equal to 1.

Percentage of total observations that lie within a range is equal to percentage of area under the curve between the corresponding values.

Explanation

The percentage of all possible observations of the variable that lie between 7 & 12 equals the area under its density curve between x> 7 & x < 12