7 The number of absences by girls from a certain class on any day is modelled by a random variable with distribution \(\operatorname { Po } ( 0.2 )\). The number of absences by boys from the same class on any day is modelled by an independent random variable with distribution \(\operatorname { Po } ( 0.3 )\).
- Find the probability that, during a randomly chosen 2-day period, the total number of absences is less than 3 .
- Find the probability that, during a randomly chosen 5-day period, the number of absences by boys is more than 3.
- The teacher claims that, during the football season, there are more absences by boys than usual. In order to test this claim at the 5\% significance level, he notes the number of absences by boys during a randomly chosen 5-day period during the football season.
(a) State what is meant by a Type I error in this context.
(b) State appropriate null and alternative hypotheses and find the probability of a Type I error.
(c) In fact there were 4 absences by boys during this period. Test the teacher's claim at the 5\% significance level.
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