20 The times taken for 200 people to complete a 5 km race were recorded. The results are summarised in the cumulative frequency diagram. (a) Use the diagram to estimate (i) the median time, (ii) the interquartile range of the times. (b) It was found that the recording of the times was inaccurate. The correct times were all one minute more than recorded. Write down the median and interquartile range of the correct times.