The burning rates of two types of propellants used in aircrew escape systems are being studied. It is known that the two types of propellants have different SD of burning rates. Two samples of n₁ = 20 and ₂ 35 specimens are tested, and sample mean burning rates are ₁ 19.05 cm/s and ₂ = 25.37 cm/s, sample SD's are s₁ = 3.81 cm/s and s2 = 3.97 cm/s. Test the hypothesis that these two types of propellants have the same mean burning rate at level a α = 0.05. =
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- A sociologist wants to determine if the life expectancy of people in Africa is less than the life expectancy of people in Asia. The data obtained is shown in the table below. Africa Asia = 63.3 yr. 1 X,=65.2 yr. 2 o, = 9.1 yr. = 7.3 yr. n1 = 120 = 150The price X (dollars per pound) and consumption y (in pounds per capita) of beef were samples for 10 randomly selected years. The following data should be used to answer the question that follows. n = 10 Ex = 36.19 Ix² = 134.17 2.9 < x s 6.2 Ey = 774.7 Iy² = 60739.23 Exy = 2832.21 Using this data, a student calculated SSy = 28.43 SSx = 3.2 SSy= 717. Calculate the %3D %3D value of the standard error or regression, Se , and enter you answer accurate to the nearest hundredth (2 decimal places).A certain chemical pollutant in the Pasig River has been constant for several years with mean u = 34 ppm (parts per million). A group of industry representatives claim that their waste management programs have lowered this average significantly.
- Suppose u, and u, are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. The data follows: m = 9, x = 115.5, s, = 5.04, n = 9, y = 129.9, and s, = 5.37. Calculate a 95% CI for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2. (Round your answers to two decimal places.) n USE SALT |-19.56 Does the interval suggest that precise information about the value of this difference is available? O Because the interval is so narrow, it appears that precise information is not available. O Because the interval is so wide, it appears that precise information is not available. O Because the interval is so wide, it appears that precise information is available. O Because the interval is so narrow, it appears that precise information is available.Suppose u, and µ, are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. The data follows: m = 7, x = 113.3, s, = 5.02, n = 7, y = 129.8, and s, = 5.32. Calculate a 95% CI for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2. (Round your answers to two decimal places.) n USE SALT |-22.52 |-10.48 Does the interval suggest that precise information about the value of this difference is available? O Because the interval is so wide, it appears that precise information is available. O Because the interval is so narrow, it appears that precise information is not available. O Because the interval is so wide, it appears that precise information is not available. O Because the interval is so narrow, it appears that precise information is available.The "spring-like effect" in a golf club could be determined by measuring the coefficient of restitution (the ratio of the outbound velocity to the inbound velocity of a golf ball fired at the clubhead). Twelve randomly selected drivers produced by two clubmakers are tested and the coefficient of restitution measured. The data follow: Club 1: 0.8406, 0.8104, 0.8234, 0.8198, 0.8235, 0.8562, 0.8123, 0.7976, 0.8184, 0.8265, 0.7773, 0.7871 Club 2: 0.8305, 0.7905, 0.8352, 0.8380, 0.8145, 0.8465, 0.8244, 0.8014, 0.8309, 0.8405, 0.8256, 0.8476 Test the hypothesis that both brands of ball have equal mean overall distance. Use α = 0.05 and assume equal variances. Question: Reject H0 if t0 < ___ or if t0 > ___.
- Fifty male subjects drank a measured amount x (in ounces) of a medication and the concentration y (in percent) in their blood of the active ingredient was measured 30 minutes later. The sample data are summarized by the following information: n = 50 Ex = 112.5 Ex? = 356.25 %3D Ey = 4.83 Ey = 0.667 Exy = 15.255 0 < x < 4.5 Or= 0.875 Or= 0.709 Or= -0.846 Or=0.460 Or= 0.965Sulfur compounds cause "off-odors" in wine, and winemakers want to know the odor threshold – the lowest concentration of a compound that the human nose can detect. The odor threshold for dimethyl sulfide (DMS) in trained wine tasters is about 25 micrograms per liter of wine (µg/L). The untrained noses of consumers may be less sensitive, however. A set of DMS odor threshold data for 10 untrained students was analyzed. How sensitive are the untrained noses of students? You want to estimate the mean DMS odor threshold among all students, and you would be satisfied to estimate the mean to within ±0.25 with 95% confidence. The standard deviation of the odor threshold for untrained noses is known to be o = 8 micrograms per liter of wine. How large an SRS of untrained students do you need? Give your answer rounded up to the nearest whole number. n = IncorrectEach year the US Environmental Protection Agency (EPA) releases fuel economy data on cars manufactured in that year. Below are summary statistics on fuel efficiency (in miles/gallon for city driving) from random samples of cars with manual and automatic transmissions manufactured in 2012. We want to know if there is a statistical difference between the average fuel efficiencies between the two different types of transmission. Automatic Transmission Manual Transmission X1 = 15.7 Si = 3.6 N1 = 26 T2 = 19 S2 = 4.65 N2 = 34 Mean %3D SD Sample Size (a) Calculate the standard error for the appropriate sampling distribution: SE = (b) We want to calculate a 91% confidence interval for the difference between the gas mileages for the automatic transmission and the manual transmission cars. What is the critical t-score that we should use to build our confidence interval? tcritical (c) Calculate the margin of error, the lower bound, and the upper bound for the 91% confidence interval. Margin of…
- Suppose u, and u, are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. The data follows: m = 5, x = 115.1, s, = 5.05, n = 5, y = 129.2, and s, = 5.36. Calculate a 95% CI for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2. (Round your answers to two decimal places.) n USE SALT Does the interval suggest that precise information about the value of this difference is available? O Because the interval is so narrow, it appears that precise information is available. o Because the interval is so wide, it appears that precise information is not available. o Because the interval is so narrow, it appears that precise information is not available. Because the interval is so wide, it appears that precise information is available. You may need to use the appropriate table in the Appendix of Tables to answer this question.In a Ni-Cd battery, a fully charged cell is composed of nickelic hydroxide. Nickel is an element that has multiple oxidation states. Assume the following proportions of the states: Nickel Charge Proportions Found 0 0.17 +2 0.33 +3 0.33 +4 0.5-0.33 Determine the variance of the nickel charge. Please enter the answer to 3 decimal places.Cell Phone Radiation Listed below are the measured radiation absorption rates (in W/kg) corresponding to these cell phones: iPhone 5S, BlackBerry Z30, Sanyo Vero, Optimus V, Droid Razr, Nokia N97, Samsung Vibrant, Sony Z750a, Kyocera Kona, LG G2, and Virgin Mobile Supreme. The data are from the Federal Communications Commission (FCC). The media often report about the dangers of cell phone radiation as a cause of cancer. The FCC has a standard that a cell phone absorption rate must be 1.6 W/kg or less. If you are planning to purchase a cell phone, are any of the measures of center the most important statistic? Is there another statistic that is most relevant? If so, which one?