The interval of hours represents the lifespan of the middle 68% of light bulbs, using the empirical rule is, 1210 hours to 1390 hours.

<h3>What is empirical rule?</h3>

According to the empirical rule, also known as 68-95-99.7 rule, the percentage of values that lie within an interval with 68%, 95% and 99.7% of the values lies within one, two or three standard deviations of the mean of the distribution.

$P(\mu - \sigma < X < \mu + \sigma) = 68\%\\P(\mu - 2\sigma < X < \mu + 2\sigma) = 95\%\\P(\mu - 3\sigma < X < \mu + 3\sigma) = 99.7\%$

Here, we had where mean of distribution of X is \mu and standard deviation from mean of distribution of X is \sigma

The amount of time a certain brand of light bulb lasts is normally distributed with a mean of 1400 hours and a standard deviation of 50 hours. Thus,

$\mu=1300\\\sigma=90$

Using the empirical rule, the interval of hours represents the lifespan of the middle 68% of light bulbs is,

$P(\mu - \sigma < X < \mu + \sigma) = 68\%\\P(1300- 90 < X < 1300+ 90) = 68\%\\P(1210 < X < 1390) = 68\%$

Thus, the interval of hours represents the lifespan of the middle 68% of light bulbs, using the empirical rule is, 1210 hours to 1390 hours.

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3 0

2 years ago

Plz help brainliest to first answer **HELP** plz

AlexFokin [52]

Answer:

Angle UST= 180

Step-by-step explanation:

Im not so sure but angle U= 25 degrees+ angle S=95 degrees+ angle T=60 degrees. Dont rely on me too much I'm only a middle school kid that got put in a highschool course for some apparent reason.

3 0

2 years ago