2. you want to see if fifth-grade boys or fifth-grade girls are faster at solving ken-ken puzzles. you randomly select twenty fifth-grade boys and twenty fifth-grade girls from
fifth graders in your school district. you time and record how long it takes each student to solve the same ken-ken puzzle correctly.

It is an Observational study. The population of interest is fifth-grade boys and girls in your school district.

Step-by-step explanation:

Consider the provided information.

Observational study is the study in which observer only observe the subjects, and measure variables of interest without allocating treatments to subjects.

Experiment study is the study in which the researchers are applying treatments to experimental units in the research, then the effect of the treatments on the experimental units is observed.

Now consider the provided survey.

Here, students are randomly selected form the population of fifth-grade boys and girls.

The aim of the study is to observe the subjects and no treatment was administered to the students.

Thus. it is an Observational study.

Thepopulation of interest is fifth-grade boys and girls in your school district.

The study is to observe who is faster fifth-grade boys or fifth-grade girls at solving Ken-Ken puzzles.