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The question is incomplete! Complete question along with answer and step by step explanation is provided below.
Question:
The lifetime (in hours) of a 60-watt light bulb is a random variable that has a Normal distribution with σ = 30 hours. A random sample of 25 bulbs put on test produced a sample mean lifetime of = 1038 hours.
If in the study of the lifetime of 60-watt light bulbs it was desired to have a margin of error no larger than 6 hours with 99% confidence, how many randomly selected 60-watt light bulbs should be tested to achieve this result?
Given Information:
standard deviation = σ = 30 hours
confidence level = 99%
Margin of error = 6 hours
Required Information:
sample size = n = ?
Answer:
sample size = n ≈ 165
Step-by-step explanation:
We know that margin of error is given by
Margin of error = z*(σ/√n)
Where z is the corresponding confidence level score, σ is the standard deviation and n is the sample size
√n = z*σ/Margin of error
squaring both sides
n = (z*σ/Margin of error)²
For 99% confidence level the z-score is 2.576
n = (2.576*30/6)²
n = 164.73
since number of bulbs cannot be in fraction so rounding off yields
n ≈ 165
Therefore, a sample size of 165 bulbs is needed to ensure a margin of error not greater than 6 hours.
Hello!
First of all, we can see that our y-intercept is 0. As you can see, for every 1 x value, we have 3 y values. We divide, giving us a slope of 3.
Therefore, our equation is y=3x.
I hope this helps!
Step-by-step explanation:
Given
Lin walks half a mile at a constant rate i.e. Lin velocity is constant. So, in the graph, it will be a straight line through the origin.
Lin is still for five minutes and after she began sprinting for the slip up to halfway i.e. Lin is accelerating or velocity is increasing for the halfway and later she started walking for the rest of the way.
Answer: $1.33.
Step-by-step explanation:
Earnings per share = (Net income - Preferred dividends) / Common shares outstanding
Preferred dividends = 10,000 shares * 50 * 10%
= $50,000
Earnings per share = (150,000 - 50,000) / 75,000
= $1.33
