The mean ( average ) is given as 1200 hours.
The standard deviation is 200, sample size is 100.
Find the standard error:
√(200^2 / 100) = 20
Now calculate the confidence interval. For 95% the Z number is 1.96
Multiply Z by the standard error:
1.96 x 20 =39.2
Now find the range that the mean should be within:
1200 - 39.2 = 1160.8
1200 + 39.2 = 1239.2
The samples should be between 1160.8 and 1239.2 for a 95% confidence interval.
Since the average was 1050, which is below 1160.8 the bulbs are not in compliance.
I wish I could help but I'm not good in math at all
Step-by-step explanation:
It is required to find the expressions that are equivalent to 4-x. We can also write it as :
Option (b) : (4-x) = 4+(-x)
Option (c) : (4-x) = -x+4
Hence, the correct options are (B) and (C).
