1. 1.A population has a mean of 75 and a standard deviation of 17.4. A sample of 35 items is randomly selected from this population . What is the probability that the mean of this sample lies between 72 and 79? 2. An electronic company in Laguna manufactures resistors that have a mean resistance of 120 ohms and a standard deviation of 13 ohms . Find the probability that a randomly sample of 40 resistors will have an average resistance greater than 114 ohms II. 1. A manufacturer of light bulbs produces bulbs that last a mean of 950 hours with a standard deviation of 120 hours . What is the probability that the mean lifetime of a random sample of 10 of these bulbs is less than 900 hours ? 2. In a study of life expectancy of 400 people in a certain geographic region , the mean age at death was 70 years , and the standard deviation was 5.1 years . If a sample of 50 people from this region is selected , what is the probability that the mean life expectancy will be less than 68 years? III. 1. The average public high school has 468 students with a standard deviation of 87