A researcher wants to conduct a study to see if cell phones cause headaches. The researcher finds 30 individuals who use cell phones regularly and 30 that do not. Each of the 60 individuals are given a questionnaire designed to determine headache frequency. If the 60 individuals did not know they were participating in the study, which statement about the study is correct? a. It is an experiment where cell phone habits is a blocking variable.
b. It is an observational study.
c. It is a matched-pairs design.
d. It is a randomized experiment.
e. It is a double-blind study.

E. It is a double-blind study.

Step-by-step explanation:

This is a double blind study since the 60 individuals who partake in the study did not know they were participating in the study,

A double-blind study is a kind of study whereby the participants involved do not know that they are participating in a study and also don't know who'll end up getting a certain treatment. The aim of this is so that bias can be prevented in the study.

in 2010, the population of the state of california is 37.29 × 10⁶

step-by-step explanation:

population of los angeles = 3.79 × 10⁶

population of california = 9.84 × population of los angeles

                                        = 9.84 × 3.79 × 10⁶

                                        = 37.2936 × 10⁶

                                        = 37.29 × 10⁶

∴ in 2010, the population of the state of california is 37.29 × 10⁶