Question

The tread life of tires mounted on light-duty trucks follows the normal probability distribution with a population mean of 60,000 miles and a population standard deviation of 4,000 miles. Suppose you bought a set of four tires; what is the likelihood the mean tire life of these four tires is more than 66,000 miles?

Answer 1

Answer:

0.0013

Step-by-step explanation:

To do this, we need to use a normal distribution table with Z score values, like the one I'm attaching here.

Now, the expression to calculate the Z value is the following:

Z = x - μ / (σ/√n)

Where:

μ: mean

σ: standard deviation

x: value required

n: sample population

Now that we have the data, let's calculate the Z value:

Z = 66,000 - 60,000 / (4000/√4)

Z = 3

Now, let's look at the table to get the value that belongs to this Z score. According to the table, it's 0.0013

Therefore, the likelihood would be 0.0013