Given data:
The given mean life is m=50 months.
The given standard deviation is s=6 months.
The given value of battery life is x= 48 months.
The expression for the probability of that a randomly selected battery will last less than 48 months is,
Refere the Z-table the value of the above expression is 0.3707.
Thus, the probability that a randomly selected battery will last less than 48 months is 0.3707.