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Karo-lina-s [1.5K]
1 year ago
9

The life of a manufacturer's compact fluorescent light bulbs is normal, with mean 12,000 hours and standard deviation 2,000 hour

s. Seth wants to find the probability that a light bulb he purchased from this manufacturer will last no more than 14,500 hours.
How many standard deviations above the mean is 14,500 hours?
Mathematics
2 answers:
ikadub [295]1 year ago
4 0
Mean = 12000
Standard Deviation = 2000

We have to find how many standard deviations is 14,500 away from the mean.
This can be achieved by calculating the z-score

Z-score tells us how many standard deviations above or below is a sample value from the mean. A positive z value shows, sample value is above the mean.

z score can be calculated as = (Sample Value - Mean )/Standard Deviation)
So,
Z-score = \frac{14500-12000}{2000} =1.25

This means, 14,500 is 1.25 standard deviations above the mean value 12,000.
Kipish [7]1 year ago
3 0

The first question: "How many standard deviations above the mean is 14,500 hours?"

Answer: A. 1.25

The second question: "Using the standard normal table, the probability that Seth’s light bulb will last no more than 14,500 (P(z ≤ 1.25)) hours is about___."

Answer: 89%


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Let Lisa's height be x, Ian's be y and Jim's be z
x = 10 + y . . . (1)
y = 14 + z . . . (2)
y + 14 + z + 14 = 170 + x + 14
y + z - x = 170 + 14 - 28 = 156 . . . (3)
From (2), z = y - 14 . . . (4)
Putting (1) and (4) into (3) gives,
y + y - 14 - 10 - y = 156
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Therefore, Ian's height is 180 centimeters
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Answer:

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Step-by-step explanation:

The hypothesis for this test is:

<em>H</em>₀: The average number of homeless people is not increasing, i.e. <em>μ</em> = 42.3.

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As the population standard deviation is provided use a single mean <em>z</em>-test for the hypothesis testing.

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