Respuesta :
Using F-distribution, the mean braking distance of four-cylinder cars is greater than the mean braking distance of six cylinder cars.
What is F-distribution?
F-distribution is "probability density function especially is used in analysis of variance and is function of ratio of two independent random variable each of which has chi-square distribution and its divided by number of degrees of freedom".
According to the question,
sample size n₁ =13 four cylinder cars
sample size n₂ = 12 six cylinder cars
mean of four cylinder cars μ= 137.5ft
mean of six cylinder cars μ= 136.3ft
standard deviation S₁² = 5.8ft
standard deviation S₂² = 9.7ft
H₀:S₁² > S₂² (The mean braking distance of four-cylinder cars is greater than the mean braking distance of six cylinder cars)
H₁:S₁²≠S₂² (The mean braking distance of four-cylinder cars is not greater than the mean braking distance of six cylinder cars)
Formula for F-distribution = S₁²/S₂²
= 5.8/9.7 =0.59793
Formula to calculate number of degrees of freedom for F-distribution (n₁-1,n₂-2).
= (13-1,12-2)
=(12,10)
The significant values of F - distribution for left tailed test at 0.05 level of significance. Tabulated F₍₁₂,₁₀₎ values lies between 2.76 to 4.30. Since, calculated values F-distribution is less than the tabulated value F₍₁₂,₁₀₎. H₀ may be accepted.
Hence, The mean braking distance of four-cylinder cars is greater than the mean braking distance of six cylinder cars.
Learn more about F-distribution here
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