Need Help on All please! Over the entire six years that students attend an Ohio

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Need Help on All please! Over the entire six years that students attend an Ohio elementary school, they are absent, on average. 28 days due to influenza. Assume that the standard deviation over this time period is sigma = 9 days. Upon graduation from elementary school, a random sample of 36 students is taken and asked how many days of school they Suppose that, on average, electricians earn approximately mu = 54, 100 dollars per year in the United States. Assume that the distribution for electrician's yearly earnings is normally distributed and that the standard deviation sigma = 12, 000 dollars. Given a sample of four electricians, what is the standard deviation for the sampling distribution of the sample mean? Suppose that, on average, electricians earn approximately mu = 54, 100 dollars per year in the United States. Assume that the distribution for electrician's yearly earnings Is normally distributed and that the standard deviation is sigma = 12, 000 dollars. What is the probability that the average salary of four randomly selected electricians exceeds $60, 000? A random sample of size 100 is taken from a population described by the proportion mu = 0.60. The probability that the sample proportion is greater than 0.62 is ___. A random sample of size 100 is taken from a population described by the proportion p = 0.60. The probability that the sample proportion is less than 0.55 is ____. A random sample of size 100 is taken from a population described by the proportion p = 0.60. The probability that the sample proportion is between 0.55 and 0.62 is ____. Customers at Wholefoods spend an average of $100.00 per trip. One of Wholefoods rivals would like to determine whether Its customers sped more per trip. A survey of 36 customers found that the sample mean was $150.00. Assume that the standard variation is $10.00 and that spending follows a normal distribution. (a) Specify the appropriate null and alternative hypotheses. (b) Calculate the value of the test statistic and the p-value. (c) At the 5% significance level, what is the conclusion of the test? (d) Repeat the test using the critical value approach.

Explanation / Answer

5.) µ = 28, = 9, n = 36

P(25 X 30) = P(X = 30) - P(X = 25)

= P(z = (30 - 28) / (9/36)) - P(z = (25 - 28) / (9/36))

= P(z = 1.33) - P(z = -2)

= 0.9082 - 0.02275

= 0.8854

7.) µ = 54,000; = 12,000; n = 4

P(X > 60,000) = P(z > (60000 - 54000) / (12000/4))

= P(z > 1)

= 1 - P(z 1) = 1 - 0.8413

= 0.1587

8.) p = 0.6; n = 100; = (p(1-p) / n) = 0.0489

P(p > 0.62) = P( z > (0.62 - 0.6) / 0.0489)

= P(z > 0.4082)

= 1 - P(z > 0.4082) = 1 - 0.8156

= 0.1844

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