1) The freshmen at state university took a biology test. The scores were distributed normally with...

1) The freshmen at state university took a biology test. The scores were distributed normally with a mean of 70 and a standard deviation of 5.
a) What percentage of scores are between 65 and 75?
b) What scores are between 60 and 85?
c) What scores are greater than 80 ?
2) The juniors at Central High School took the ACT last year. The scores were distributed normally with a mean of 24 and a standard deviation of 4.
a) What percentage of scores are between scores 20 and 28?
b) What percentage of scores are between 16 and 28 ?
c) What percentage of scores are greater than 24?
3) The diameters of grapefruit in a certain orchard are normally distributed with mean 4.6 inches and a standard deviation of 1.3 inches. If a random sample of 10 of these grapefruit are put in a bag and sold what is the probability that the mean diameter of the grapefruit in the bag will be
a) Greater than 5 inches.
b) Less than 4 inches
4) Walter usually meets Julia at the track. He prefers to jog 3 miles. From long experience, he knows that σ = 2.40 minutes for his jogging times. For a random sample of 90 jogging sessions, the mean time was 22.50 minutes. Let μ be the mean jogging time for the entire distribution of Walter’s 3-mile running times over the past several years. Find a 0.99 confidence interval for μ.

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orchestra answered 1 year ago

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