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ivann1987 [24]
2 years ago
12

The Office of Student Services at a large western state university maintains information on the study habits of its full-time st

udents. Their studies indicate that the mean amount of time undergraduate students study per week is 20 hours. The hours studied follows the normal distribution with a population standard deviation of seven hours. Suppose we select a random sample of 125 current students. What is the probability that the mean of this sample is between 19.25 hours and 21.0 hours
Mathematics
1 answer:
ExtremeBDS [4]2 years ago
8 0

There is a probability of 77% that the mean of this sample is between 19.25 hours and 21.0 hours

Z score is used to determine by how many standard deviations the raw score is above or below the mean. The z score is given by:

z=\frac{x-\mu}{\sigma/\sqrt{n} } \\\\where\ x=raw\ score,\mu=mean,\sigma=standard\ deviation,n=sample\ size

Given that μ = 20, σ = 7, n = 125.

For x = 19.25:

z=\frac{19.25-20}{7/\sqrt{125} } =-1.20\\\\\\For\ x=21:\\\\z=\frac{21-20}{7/\sqrt{125} } =0.62

From the normal distribution table, P(-1.20 < z < 0.62) = P(z < 0.62) - P(z < -1.2) = 0.8849 - 0.1151 = 0.7698 = 77%

There is a probability of 77% that the mean of this sample is between 19.25 hours and 21.0 hours

Find out more on z score at: brainly.com/question/25638875

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Step-by-step explanation:

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<u><em>The area of the irregular figure is 140 sq. ft.</em></u>

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Owen had 18 guitars. He sold 5 guitars and kept the rest. What is the ratio of guitars he kept to guitars he sold?
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There are 1,023 M&amp;M's in a bag. Out of 1,023 M&amp;M's, 132 M&amp;M's are blue, 69 are green, 68 are brown, 63 are olive, 62
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The probability that the person pulls 1 blue M&M given that one is only allowed to pull 5 random M&M's per day will be 0.6450.

<h3>How to calculate probability?</h3>

From the information given, there are 1,023 M&M's in a bag and out of 1,023 M&M's, 132 M&M's are blue.

Therefore, the probability of getting a blue M&M will be:

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