Nayland College



Normal Distribution Practice 3Name __________________________________________1) A radar unit is used to measure speeds of cars on a motorway. The speeds are normally distributed with a mean of 90 km/hr and a standard deviation of 10 km/hr. 461010021590a) What is the probability that a car picked at random is travelling at more than 105 km/hr?461010065620904610100330454046101001361440461010012319046101005114290b) What is the probability that a car picked at random is travelling between 80 and 110 km/hr?c) What is the probability that a car picked at random is travelling at most 94 km/hr?-269900881382) For a certain type of computers, the length of time between charges of the battery is normally distributed with a mean of 50 hours and a standard deviation of 15 hours. John owns one of these computers and wants to know the probability that the length of time will be between 60 and 70 hours.-943361463803) Entry to a certain University is determined by a national test. The scores on this test are normally distributed with a mean of 500 and a standard deviation of 100. a) To be admitted to this university you must score better than 585. What percentages of applicants are admitted to this university?b) Applicants are put on a waiting list if they have test scores between 510 and 585. From a group of 1000 applicants, how many would you expect to be on the waiting list?Normal Distribution Practice 4Name __________________________________________4) The time taken to assemble a car in a certain plant has a normal distribution of 20 hours and a standard deviation of 2 hours. 46101008022590461010070535804610100620712546101005019675461010039687504610100294513046101009118604610413-2540a) What is the probability that a car can be assembled at this plant in a period of time?less than 19.5 hours??a) What is the probability that a car can be assembled at this plant in between 15 and 22 hours?5) A large group of students took a test in Physics and the final grades have a mean of 70 and a standard deviation of 10. We can approximate the distribution of these grades by a normal distribution. a) What percent of the students?scored higher than 80??b) What percent of the students should pass the test (grades≥60)??c) What percent of the students should fail the test (grades<60)?6) The annual salaries of employees in a large company are approximately normally distributed with a mean of $50,000 and a standard deviation of $20,000.?a) What percent of people earn less than $45,000??b) What percent of people earn between $48,000 and $65,000??c) How many people from a group of 500 would you expect to earn more than $72,000? ................
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