<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>
Equation would be b = 14m
Answer:
The answer is:
She used the wrong common denominator
Step-by-step explanation:
Solving the given equation
Lets consider the steps given in the question:
Lets compare both solutions:
In the original solution, the denominator of first term is (x-2)(x-3)
In the solution given in the question, the denominator of first term is (x-2)(x+3).
So the mistake she did in step 2 was that she change the sign of 3 in (x-3) from negative to positive, due to which she gets the wrong common denominator shown in Step 3.
