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 =

Answer with Step-by-step explanation:

The life of a certain brand of battery is normally distributed, with mean 128 hours and standard deviation 16 hours.

Let X be the life time of a battery.

when, X=100

the formula for z is:

z=X-mean/standard deviation

z= 100-128/16

z= -28/16

z=-1.75

P(X≤100)=P(z≤-1.75)

            = P(z≥1.75)

           =0.0409   (using z-dist table)

Hence,  probability that a battery you buy lasts at most 100 hours is:

0.0409

the 4th choice is the correct one

step-by-step explanation:

y > 1/3x

y < = -x + 4

hope this : )