The life of a certain brand of battery is normally distributed, with mean 128 hours and standard deviation 16 hours. what is the probability that a battery you buy lasts at most 100 hours? standardize the variable. x = 100 is equivalent to z =

We have been given that

mean,

standard deviation

Let us evaluate the z score using the below mentioned formula

On substituting the given values, we get

Thus, the value of z is -1.75.

Now, we find the probability that a battery you buy lasts at most 100 hours.

We will find the value for z= -1.75 using the z score table.

Hence, the required probability is 0.04006