In which of the following scenarios would an observational study be used instead of a survey or experiment ? a) a study to quantify the effect of humidity levels on plant growth b) a study to determine how age effects political preference ) to measure the level of support for a referendum d) a study to observe the effects of a medicine designed to lower cholesterol

What value is equivalent to 5 + [5 × (4 + 2)]? a) 35 b) 45 c) 60 d) 110

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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.)