A certain company produces fidget spinners with ball bearings made of either plastic or metal. Under standard testing conditions
, fidget spinners from this company with plastic bearings spin for an average of 2.7 minutes, while those from this company with metal bearings spin for an average of 4.2 minutes. A random sample of three fidget spinners with plastic bearings is selected from company stock, and each is spun one time under the same standard conditions; let x¯1 represent the average spinning time for these three spinners. A random sample of seven fidget spinners with metal bearings is selected from company stock, and each is likewise spun one time under standard conditions; let x¯2 represent the average spinning time for these seven spinners. What is the mean μ(x¯1−x¯2) of the sampling distribution of the difference in sample means x¯1−x¯2 ?
Basic savings typically offers the lowest interest rate at 0.25 % per year. It was followed by a savings bond, then the money market savings at an interest per year of 1.75 to 1.9%. Certificate of deposit showed the highest at 2.3%.
