Question

hi, can someone do the 2nd question. thanks!

Use the data in the stem-and-leaf plot to answer the following questions 27) Stem Leaf 5 6 66678 7 02334489 8 3356677 9 025 08 a) What are the highest 4 numbers represented in the stem-and-leaf plot? 51, 10, 12 ,15 b) Find the range of the data set c) Find the mode d) Find the interquartile range. To estimate the mileage of a certain model car, 16 cars of that model were selected at random and tested. The mean of the sample was 22.4 mpg and the standard deviation of the sample was 2.8 mpg Find a 95% confidence intervalfr the mean mileage Show all your work as you calculate E. Clearly indicate if you used z or t in the calculation. 957 2-2 2-13 2-12 -213 Confidence Interval: (20-101, 23. 22.f When the alignment of a car is off, it can lead to lower gas mileage than usual. A car of this same model has a gas mileage of 19 mpg. Could it be experiencing alignment problems? Use the confidence interval to explain why or why not.

Answer 1

Answer 28:

Part 1

The provided sample mean is 22.4 and the sample standard deviation is s 2.8. The size of the sample is n-16 and the required confidence level is 95%. The number of degrees of freedom are df = 16-1 = 15, and the significance level is α = 0.05. Based on the provided information, the critical t-value for a- 0.05 and df 15 degrees of freedom is te 2.131 The 95% confidence for the population mean μ is computed using the following expression Therefore based on the information provided the 95 % confidence for the population mean s 2.131×28 16 224+ 2131 x 2.8 CI= (22.4 16 (22.4-1.492,22.4+1492) (20.908, 23.892)

Interpretation of Confidence Interval

We are 95% confident that population mean mileage will be between (20.908, 23.892)

Part 2

It is given in the question that gas mileage of the car is 19 mpg.

If the alignment of car is not off, it should have mileage within the confidence interval (20.908, 23.892).

In this case, gas mileage of car (19 mpg) does not lie within the confidence interval (20.908, 23.892). Thus, it can be inferred that alignment of car is off. In other words, car could be experience alignment problem.