One problem facing the manager of maintenance departments is when to change the bulbs in streetlamps. if bulbs are changed only when they burn out, it is quite costly to send crews out to change only one bulb at a time. this method also requires someone to report the problem and, in the meantime, the light is off. if each bulb lasts approximately the same amount of time, they can all be replaced periodically, producing significant cost savings in maintenance. suppose that a financial analysis of the lights at yankee stadium has concluded that it will pay to replace all of the light bulbs at the same time if the variance of the lives of the bulbs is less than . the lengths of life of the last 100 bulbs were recorded. what conclusion can be drawn from these data? use a 5% significance level.

the first one, all those points on the line just make a strait line.

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.

addition

step-by-step explanation: