Question

select all the correct answers. a manufacturer claims that its new hand sanitizer reduces the number of days an average person is sick in a year. to test this claim, a researcher decided to conduct an experiment. the researcher randomly selected 300 people, divided into subject groups by age. over the course of a year, subjects regularly used the hand sanitizer. at the end of the year, the researcher compared the number of days that the subjects in each group were sick. which statements about this experiment are true? this study uses blinding. this study uses random sampling. this study uses a control group. this study uses blocking. this study uses a repeated measures design.

Explanation:

1. Blinding is not mentioned, so we can't assume it's used.
2. The researcher randomly selected 300 people, which is random sampling.
3. There's no mention of a control group (a group not using the hand - sanitizer for comparison).
4. Dividing subjects by age is blocking as it groups similar subjects together.
5. There's no indication of repeated measures (same subjects measured multiple times under different conditions).

Answer:

B. This study uses random sampling.
D. This study uses blocking.