4b is equivalent to b+b+b+b
12-4=8 which means 12-8=4 which means now you have the difference of 4 and 8+4=12 which means now you have the sum of 12
Answer: (C) 0.1591
Step-by-step explanation:
Given : A manufacturer of radial tires for automobiles has extensive data to support the fact that the lifetime of their tires follows a normal distribution with


Let x be the random variable that represents the lifetime of the tires .
z-score : 
For x= 44,500 miles

For x= 48,000 miles

Using the standard normal distribution table , we have
The p-value : 

Hence, the probability that a randomly selected tire will have a lifetime of between 44,500 miles and 48,000 miles = 0.1591