<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>
The sum of interior angels of a pentagon is 550
<span>11+4 (x+7)^2
Substitue 2 for x
</span><span>11+4 (2+7)^2
Multiply the numbers inside of the parenthesis by the exponent
11+4 (4+49)
Add 4 to 59
11+4 (54)
Add 4 to 11
15(54)
Multiply
Final Answer: 810</span>
