i think the answer is 35 but i am not 100% sure
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.

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,

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

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.
Learn more about empirical rule here:
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Step-by-step explanation:
If np is attitude
5x^2+10=90
5x^2=80
x^2=16
X=+-4
angle npo=90 degeees
Answer:
5´12
Step-by-step explanation:
same base 5
9+3=12
5'12