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?

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths

Girardo is using the model below to solve the equation . girardo uses the following steps: step 1 add 4 negative x-tiles to both sides step 2 add 1 negative unit tile to both sides step 3 the solution is which step could be adjusted so that gerardo's final step results in a positive x-value? in step 1, he should have added 4 positive x-tiles to both sides. in step 1, he should have added 3 negative x-tiles to both sides. in step 2, he should have added 4 negative unit tiles to both sides. in step 2, he should have added 1 positive unit tile to both sides.