- VOLUME = volume of sales. - RENT = monthly rental of computers - WORDS = number of words in the main memory in thousands - BINARY = number of binary digits per word - DIGITS = number of equivalent binary digits - MULT = average time required to obtain and complete the multiplication instruction in microseconds - ADD= average time required to obtain and complete the addition instruction in microseconds - ACCESS = average time required to access information from memory - YEAR = year in which the computer model was introduced - IBMDUM = a dummy variable taking on the value of 1 if the model was manufactured by IBM - ORDER = number of observations - For x=0,1,5, D6 x is a dummy variable taking the value 1 if the computer model was introduced in year 19610 otherwise What is the mean of D61 (rounded to three decimal places) and its internrotatinn? What is the mean of D61 (rounded to three decimal places), and its interpretation? the mean of D61 is 0.088, meaning 8.8% of the computers in the sample were introduced in year 1961 the mean is 0.500, because D61 is a dummy variable the mean is 0.088, meaning 0.088% of the computers in the sample were introduced in year 1961 none of the other options