Question

A Type I error is the mistake of ________ when it is actually true. rejecting the null hypothesisA study of the amount of time it takes a mechanic to rebuild the transmission for a 2010 Chevrolet Colorado shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time is less than 8.9 hours.

Answer 1

Question 2

Answer:

Step-by-step explanation:

Let x be a random variable representing the mean amount of time it takes a mechanic to rebuild the transmission for a 2010 Chevrolet Colorado. Given that it is normally distributed, we would calculate the z score by applying the formula,

z = (x - μ)/σ/√n

where

μ is the population mean

x is the sample mean

σ is the population standard deviation

n is the sample size

From the information given,

n = 40

x = 8.9

μ = 8.4

σ = 1.8

Thus,

z = (8.9 - 8.4)/(1.8/√40) = 1.76

We want to calculate P(x < 8.9). The probability value corresponding to z = 1.76 from the normal distribution table is 0.9608

Thus, the probability that their mean rebuild time is less than 8.9 hours is 0.9608