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3. The braking distance of a random sample of 64 cars is found to have a sample mean of 140 ft, where the population standard deviation is known from a previous study to be 9 ft. Construct a confidence interval to estimate the mean at a confidence level of 80% [3] 4. Many people feel that cereal is healthier alternative for children over glazed donuts. The data below the amount of sugar in a sample of cereal that is geared towards children. Estimate the mean amount of sugar in children's cereal using a 95% confidence interval. [4] Sugar Amounts (g) in Children's Cereal 10 14 12 9 13 13 13 6 15 11 12 15 9 10 11 3 12 12