<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>
In a triangle, the three interior angles always add to 180°
m∠B = 180 - 30 - 80 = 70°
<span>D: 70</span>
Someone is answering the question.
Answer:
<h3>
Step-by-step explanation:</h3>
A)answer: A cross section is the two-dimensional shape that results from cutting a three-dimensional with a plane.
B)answer: A cross section is the face you obtain by making a "slice" through a solid object. A cross section is two-dimensional. ... When a plane intersects a solid figure, the cross sectional face may be a point, a line segment, or a two-dimensional shape such as, but not limited to, a circle, rectangle, oval, or hexagon.
