I really don’t know but I think I got it wrong
<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>
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Now you can tell me wich is the closest number.
The common ratio is the multiplication of 2 each time. 5x2= 10// 10x2=20// 20x2=40
6x + y = 1 , y, y, -6x + 1 or 1 - 6x
