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
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 ?
A
. 3(2.7)−7(4.2)=−21.3
B
. 3−7=−4
C
. 2.7−4.2=−1.5
D
. 2.73−4.27=0.3
E. 4.2−2.7=1.5
Answer:
option C
Step-by-step explanation:
The mean of the sampling distribution of the difference of the sample means will be equal to the difference in population. Here, our answer is: 2.7 - 4.2 = -1.5.
So, to get the answer we want to add the heights of the boxes.
2 feet, 4 inches + 2 feet 11 inches = 4 feet 15 inches. 4 feet 15 inches + 3 feet 10 inches = 7 feet and 25 inches. 25 inches is equal to 2 feet and 1 inch, so we end up with 9 feet and 1 inch as our answer.