In order to estimate the mean burning time of a particular brand of bulb, 30 bulbs were left burning. The bulbs that failed are not replaced upon failure. The following burning time in hours) were recorded: 20, 27, 52, 61, 110, 122, 214, 232, 238, 371, 393, 426, 445, 472, 503, 526, 581, 627, 798, 805, 909, 976, 1001, 1016, 1033, 1086, 1192, 1322, 1681, 1723. Calculate the maximum likelihood estimate and minimum variance unbiased estimate of R(t) at t = 900 hrs.
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Answer:
Power is associated by many people with electricity. Knowing that power is the rate of energy use or energy conversion, what is the expression for electric power? Power transmission lines might come to mind. We also think of lightbulbs in terms of their power ratings in watts. Let us compare a 25-W bulb with a 60-W bulb. (See Figure 1(a).) Since both operate on the same voltage, the 60-W bulb must draw more current to have a greater power rating. Thus the 60-W bulb’s resistance must be lower than that of a 25-W bulb. If we increase voltage, we also increase power. For example, when a 25-W bulb that is designed to operate on 120 V is connected to 240 V, it briefly glows very brightly and then burns out. Precisely how are voltage, current, and resistance related to electric power?