There are 130 people in a sport centre. 65 people use the gym. 51 people use the swimming pool. 44 people use the track. 15 people use the gym and the pool. 14 people use the pool and the track. 10 people use the gym and the track. 1 person uses all three facilities. Given that a randomly selected person uses the gym and the track, what is the probability they do not use the swimming pool?

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

Need now max recorded the heights of 500 male humans. he found that the heights were normally distributed around a mean of 177 centimeters. which statements about max’s data must be true? a) the median of max’s data is 250 b) more than half of the data points max recorded were 177 centimeters. c) a data point chosen at random is as likely to be above the mean as it is to be below the mean. d) every height within three standard deviations of the mean is equally likely to be chosen if a data point is selected at random.

21 a stick 7 inches long is broken into two pieces, so that one piece is twice as long as the other one. how long are the two pieces?