Over a period of many months, a particular 5 year old boy's play activity was observed. The length of time spent in each episode of play with toys was recorded. The paper “A Temporal Analysis of Free Toy Play and Distractibility in Young Children" (Journal of Experimental Child Psychology, 1991,pages 41-69) reported the accompanying data on the play-episode lengths. (a).Use the data to calculate the density for the 20 to < 40 minute period
(b). Over a period of many months, a particular 5 year old boy's play activity was observed. The length of time spent in each episode of play with toys was recorded. The paper “A Temporal Analysis of Free Toy Play and Distractibility in Young Children" (Journal of Experimental Child Psychology, 1991,pages 41-69) reported the accompanying data on the play-episode lengths.

(a). Use the data to calculate the density for the 20 to < 40 minute period
(b). What is the probability that the play time was less than 75 seconds ?
(c). Use the data to calculate the relative frequency for the 5 to < 10 range.