1. The length of time between charges of a cellphone has a normal distribution with a mean of 30 h and a standard deviation of 8 h. If you were to observe the length of time that passes before a cellphone needs to be charged, what is the likelihood that this time will be between 24 h and 36 h? Make sure to round your answer to the nearest tenth of a percent.
2. A medical supply company produces cotton swabs that have an average length of 15.2 cm with a standard deviation of 0.3 cm. Cotton swabs that are shorter than
14.8 cm or longer than 15.6 cm will be rejected. How many cotton swabs out of the 150 000 cotton swabs that are produced by the company each day will be rejected?
3. The technical support call centre for a software company has a mean wait time of 210 s, with a standard deviation of 40 s. The management team wants to continue to improve customer satisfaction by setting a wait-time standard. If the company wants 85% of the calls to be answered within a new time specification, what maximum wait time be should used? Make sure to round your answer to the nearest second.
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