Question

The percentage of all possible observations of the variable that lie between 6 and 12 equals the area under the its density curve and expressed as a percentage.

Answer 1

The percentage of all possible observations of the variable that lie between 6 and 12 equals the area under the its density curve between 6 and 12 expressed as a percentage.

It is true for all probability density curves and total area under the curve is 1.

Because a variable with a density curve the percentage of all possible observations of the variable that lie within any specified range equal to the corresponding area under the curve expressed as a percentage