Question

What lifetime do 40% of all tires of this brand have less than? that is, what value separates the bottom 40% from the top 60% of all tires of this brand? A) 20,000 miles

B) 40,000 miles
C) 60,000 miles
D) 80,000 miles

Answer 1

The value that separates the bottom 40% from the top 60% of tires of this brand is approximately 4981.328 miles.

Step-by-step explanation:

The question asks for the value that separates the bottom 40% of tires from the top 60% of all tires of a specific brand. To find this value, we can use the standard normal distribution table and the z-score corresponding to the 40th percentile. The z-score for the 40th percentile is approximately -0.25334. Using the formula x = z*sigma + mu where x is the value, z is the z-score, sigma is the standard deviation, and mu is the mean, we can calculate the value as follows:

x = (-0.25334)(8000) + 50000 = 4981.328

So, approximately 4981.328 miles separate the bottom 40% from the top 60% of the tires of this brand.