29. An administrator at a large high school was interested in the types of school-sponsored extracurricular activities in which students participated: only academic clubs, only intramural sports clubs, both type of clubs, or neither. The responses from a survey of 300 students selected at random are summarized in the frequency table below, shown by class standing. 1 $ year 2nd year 3rd year 4th year Total Only Academics 30 40 60 60 190 Only Sports 35 30 20 20 105 Both 25 15 5 5 50 Neither 70 55 25 5 155 Total 160 140 110 90 500 If the school assumes extracurricular participation is independent of class standing, which of the following expressions could be used to calculate the expected number of respondents who do not participate in any academic or intramural activities during their 4" year at the school? ( ) = ( )= ( ) = ( )= ( )= -18