Why are the solutions to the proportions StartFraction 50 over x EndFraction = StartFraction 10 over 20 EndFraction and StartFraction 10 over 50 EndFraction = StartFraction 20 over x EndFraction the same?
because both result in the equation 20 x = 500, which simplifies to x = 25
because both result in the equation 20 x = 500, which simplifies to x = 250
because both result in the equation 10 x = 1,000, which simplifies to x = 10
because both result in the equation 10 x = 1,000, which simplifies to x = 100

In a test for esp (extrasensory perception), the experimenter looks at cards that are hidden from the subject. each card contains either a star, a circle, a wave, a cross or a square.(five shapes) as the experimenter looks at each of 20 cards in turn, the subject names the shape on the card. when the esp study described above discovers a subject whose performance appears to be better than guessing, the study continues at greater length. the experimenter looks at many cards bearing one of five shapes (star, square, circle, wave, and cross) in an order determined by random numbers. the subject cannot see the experimenter as he looks at each card in turn, in order to avoid any possible nonverbal clues. the answers of a subject who does not have esp should be independent observations, each with probability 1/5 of success. we record 1000 attempts. which of the following assumptions must be met in order to solve this problem? it's reasonable to assume normality 0.8(1000), 0.2(1000)%30 approximately normal 0.8(1000), 0.2(1000)% 10 approximately normal srs it is reasonable to assume the total number of cards is over 10,000 it is reasonable to assume the total number of cards is over 1000