<span>204
First, lookup a standard normal table and see what the z-score is for 0.025 (one half of 100% - 95%) to allow for equal sized tails. You should find that the z-score is 1.96. That means that 95% of the time, the value should be within 1.96 standard deviations of the mean. Now let's calculate the standard deviation.
800 is 800 - 1200 = -400 to the left of the mean of 1200.
1600 is 1600 - 1200 = 400 to the right of the mean of 1200.
So we are an equal distance of 400 on both sides of the mean. And we know from the z-score of 1.96, that we're 1.96 standard deviations from the mean. So a little division will give us the standard deviation. Which is:
400 / 1.96 = 204.0816327
So the standard deviation of the light bulbs is 204</span>
Answer:
(4x + 12 ) - ( -8 ) =
4x + 20
Explanation:
Just add them up and form a equation ( this is for the second one )
Answer:
B
Step-by-step explanation:
A radius is half of a diameter so multiply by 2
Answer: C
ABCD may or may not be a parellolgram. Line BD bisects line AC, however we cant figure out if line AC bisects line BD.
