After factoring out the effect of other variables known to affect SAT, such as socioeconomic status, researchers found that music students had a higher SAT score than non-music students. This is an example of .1. None of the other answers is correct2. Observational Study3. Comparative study

Use the frequency distribution, which shows the number of american voters (in millions) according to age, to find the probability that a voter chosen at random is in the 18 to 20 years old age range. ages frequency 18 to 20 5.9 21 to 24 7.7 25 to 34 20.4 35 to 44 25.1 45 to 64 54.4 65 and over 27.7 the probability that a voter chosen at random is in the 18 to 20 years old age range is nothing. (round to three decimal places as needed.)