Step-by-step explanation:
For non zero X and Y if X + Y = 0 then
1 answer:
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Answer:
We need at least 217 compact fluorescent light bulbs
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find M as such
In which is the standard deviation of the population and n is the size of the sample.
How many compact fluorescent light bulbs need to be selected?
We need at least n bulbs, in which n is found when
So
We need at least 217 compact fluorescent light bulbs
Given:
A chemical company makes two brands of antifreeze.
The first brand is 70% pure antifreeze.
The second brand is 95% pure antifreeze.
We need to make 130 gallons of a mixture that contains 85% pure antifreeze.
Let we will use (x) gallons from the first brand
So, we will use (130 - x) from the second brand.
The mixture must contain 85% pure antifreeze.
So, we can write the following equation:
Solve the equation to find (x):
So, the answer will be:
First brand: 52 gallons
Second brand: 78 gallons