Question

The area under the density curve that lies to the right of 15 is 0.324. What percentage of all possible observations of the variable

a. exceed 15 ?

b. are at most 15 ?

Short answer

Percentage of variable's observations that exceed $15=32.4\%$

Percentage of variable's observations that are at most$15=67.6\%$

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 =$45.3Kgs$

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 

As under the density curve that lies to the right of $15=0.324$out of total area = $1$, so percentage of observations more than $15=32.4\%$

Hence, percentage of observations that are at most $15$include observations that are less than or equal to 15. These observations are to the left of $15$, so $1-0.324=67.6\%$