6. In a survey, 45% of the interviewees are of age below 30, 30% are between 30 and 50, and 25% are above 50. 90% of the interviewees aged below 30, 60% of the interviewees aged between 30 and 50, and 70% of the interviewees aged above 50 can swim. (a) If a randomly selected interviewee can swim, find the probability that his/her age is between 30 and 50. (b) If a randomly selected interviewee cannot swim, find the probability that his/her age is below 30. (Give your answers correct to 3 significant figures if necessary.) (7marks)