The lighthouse keeper that is at the top of a lighthouse that
1 answer:
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First set up the equation to find answer: y=7-x. Then add it to the variable. 3x-1(7-x)=1. So that makes it 3x+-7+-1=1. Add like terms -7+-1=-8, so 3x+-8=1. Now to find x just switch the 8 to the other side. So you end up with 3x=9 since when you take away a number from one side you need to use the opposite value so adding 8 to -8 will cancel it out, then add it to the other, then just divide. 9/3=3, from here just substitute to find y. y=7+3. y=10. The answer is x=2 and y=5. I hope I helped!
Answer:
The bulbs should be replaced each 1060.5 days.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
How often should the bulbs be replaced so that no more than 1% burn out between replacement periods?
This is the first percentile, that is, the value of X when Z has a pvalue of 0.01. So X when Z = -2.325.
The bulbs should be replaced each 1060.5 days.