Question

The burning time of a very large candle is normally distributed, with a mean of 2500 hours and a standard deviation of 20 hours. find the z-score that corresponds to a lifespan of 2470 hours.

a. 2.5
b. 1.5
c. -1.5
d -2.5​

Answer 1

Value of z-score is -1.5

Option C is correct.

Explanation:

We are given

Mean = 2500 hrs

Standard Deviation = 20 hours

X = 2470

We need to find z-score

The formula used to calculate z-score is:
`z-score=(x-\mu)/(\sigma) \\`

Putting values of x, mean and standard deviation in the formula

`z-score=(x-\mu)/(\sigma) \\z-score=(2470-2500)/(20) \\z-score=-1.5`

So, value of z-score is -1.5

Option C is correct.