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1) In professional tennis, the length of time that the strings of a tennis racquet last is distributed uniformly anywhere from 5 to 30 days.

Calculate the probability that the strings last longer than 10 days but less than 20 days. Round your answer to 2 digits after the decimal. Answer (0.40 )

2) In professional tennis, the length of time that the strings of a tennis racquet last is distributed uniformly anywhere from 5 to 30 days.

Given that the strings are still not broken on day 15 since they were strung, what is the probability that the strings will not break for at least another 10 days? Round your answer to 2 digits after the decimal. Answer (0.33)

3) According to a survey of advanced curriculum high school students, the mean time spent studying each day is 5 hours. Assume the standard deviation is 0.8 hours and that the probability distribution is normal.

What is the probability that a randomly selected student studies 4 hours per day or less? Choose closest to the correct answer option. Answer( 0.11)

4) According to a survey of advanced curriculum high school students, the average time spent studying each day is 6.4 hours. Assume the standard deviation is 0.80 hours and that the probability distribution is normal.

Teachers want to warn students whose studying times are in the bottom 25%. What is the cut-off of studying time of the students who the teachers would like to warn? Choose the option closest to your answer.

Answer( 4.7)

5) A cyber hacker is trying to identify the mean age of customers that make frequent purchases on the online retail platform. The hacker does not have access to the raw data, however, the hacker had guessed that the age of customers is normally distributed with a standard deviation of 5 years.

In addition to the above, the hacker knows that 70% of the time the age of the customers does not exceed 30 years old. Calculate the mean age of customers, relying on the above information. Answer (27.38)