Z value is a numerical measurement that describe a value relationship to the mean of a group of values. The standard deviations is 1.25 above the mean is 14,500 hours.
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Given information-</h3>
The mean for the bulb is 12,000 hours.
The standard deviation for the bulb is 2000 hours.
Sample value is 14500.
To find out the how many standard deviation is 14500 mean away from the mean the z value of the mean should be calculated.
<h3>Z value</h3>
Z value is a numerical measurement that describe a value relationship to the mean of a group of values. Z value is the ratio of the difference of the sample value 
and mean 
to the standard deviation. Thus the z value for the given mean 
is,
Thus the standard deviations is 1.25 above the mean is 14,500 hours.
Learn more about the z value here;
brainly.com/question/62233
Answer:666 hours
Step-by-step explanation: The reason is that if you turn the problem into an equation it would be h=Lx. h= hours. L=how long the log lasts and x=how many logs. So when you plug in the numbers you get 101010=L*151515. So we need to find L. What you do is you divide both sides by 151515 since it is the opposite of multiplication. 151515/151515 gets crossed out and 101010/151515 is .6666666666666 irrational. So the equation now looks like .666666 irrational=L. So .66666 irrational is your L. Know you plug .666666 irrational into your original equation. Which is now h=.6666 irrational*x. So to find how long the fire keeps on burning with 999 logs you just plug 999 into x and now your equation looks like this h=.6666 irrational*999. If you multiply .6666 irrational by 999 your final answer is 666.
Algebra
Use the distributive property to make 5x+5.
5x+5<25
Subtract 5 from both sides.
5x<20
Divide both sides by five.
x<4
You've found the prime factorization when all of your factors are prime. They can't be divided into any smaller factors.
