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.

correct answer is infinitely many solutions

step-by-step explanation:

2(2x + 3) = -4 + 2(2x + 5)

solving the above equation:

4x + 6 = -4 +4x +10

combining like terms

4x -4x = -4+10-6

0=0

since both sides are 0=0, we end up into true statement it means it has infinite many solutions.

so correct answer is infinitely many solutions