Answer: the value of shell life is 9.2 hours.
Step-by-step explanation:
Since the shelf life of a battery produced by one major company is known to be normally distributed, we would apply the formula for normal distribution which is expressed as
z = (x - µ)/σ
Where
x = shelf life of a batteries in years.
µ = mean shell life
σ = standard deviation
From the information given,
µ = 9 years
σ = 0.2 years
Looking at the normal distribution table, the z score corresponding to the p value of 16%(16/100 = 0.16) is - 0.9. Therefore
- 0.9 = (x - 9)/0.2
0.2 × - 0.9 = x - 9
0.18 = x - 9
x = 0.18 + 9
x = 9.2
