The lifetime of a 2 volt non- rechargeable battery has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours.What is the z- score for batteries with lifetimes of 600 hours

z-score = (X-μ)/σ

μ=mean
σ=standard deviation
X=value of random variable (600)

To find the z-score for batteries with a lifetime of 600 hours, we need to use the formula:

z = (x - μ) / σ,

where:
- z is the z-score,
- x is the value we want to find the z-score for (in this case, 600 hours),
- μ is the mean of the distribution (516 hours),
- and σ is the standard deviation of the distribution (20 hours).

Plugging the values into the formula, we get:

z = (600 - 516) / 20 = 84 / 20 = 4.2.

Therefore, the z-score for batteries with lifetimes of 600 hours is 4.2.