<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:
It's A
Step-by-step explanation:
I hope that it's a correct answer.
Answer:
Step-by-step explanation:
1 Simplify 19-7 to 12.
12^2−8×3+4×3−5
2 Simplify 12^2 to 144
144−8×3+4×3−5
3 Simplify 8×3 to 24.
144−24+4×3−5
4 Simplify 4×3 to 12.
144−24+12−5
5 Simplify 144-24 to 120.
120+12-5
6 Simplify 120+12 to 132.
132-5
7 Simplify.
127
