Answer:
0.8413 = 84.13% probability of a bulb lasting for at most 605 hours.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean 
and standard deviation 
, the z-score of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
The standard deviation of the lifetime is 15 hours and the mean lifetime of a bulb is 590 hours.
This means that 
Find the probability of a bulb lasting for at most 605 hours.
This is the pvalue of Z when X = 605. So
has a pvalue of 0.8413
0.8413 = 84.13% probability of a bulb lasting for at most 605 hours.
Answer:
90 mi/h
Step-by-step explanation:
Given,
For first 30 miles, her speed is 30 miles per hour,
Let x be her speed in miles per hour for another 30 miles,
Since, here the distance are equal in each interval,
So, the average speed of the entire journey
According to the question,
Hence, she needs to go 90 miles per hour for remaining 30 miles.
Answer:
30
Step-by-step explanation:
Two or zero expresses the possible number of positive real solutions for the given polynomial equation.
Answer: Option D
<u>Step-by-step explanation:</u>
Given equation:
First, we put hit and trial method to find out the one solution. So, if we put x=4 then the above expression will become zero. We can also write the above expression as
We know the formula, 
, make use of this, we get
So, 
Hence, from the above expression, we have three values of x as x= 4, 2.64 and -2.64
The answer is: " -5/3 " ; or, write as: " -1 ⅔ " .
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Explanation:
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(-5/6) + (-5/6) = (-5/6) <span>− (5/6) ;
------> {since: "adding a negative" is the same a "subtracting a positive"} ;
------> </span> (-5/6) − (5/6) = (-5 − 5) / 6 ;
= -10/6 = (-10/2) / (6/2) ;
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= " -5/3 " ; or, write as: " -1 ⅔ " .
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