A random sample of n = 64 observations has a mean x = 29.9 and a standard deviation s = 3.7.

Mathematics

1 answer:

Elis [28]3 years ago

4 0

Answer:

(29.128,30.672)

Step-by-step explanation:

Given that a random sample of n = 64 observations has a mean x = 29.9 and a standard deviation s = 3.7.

a) the point estimate of the population mean μ.

= Sample mean = 29.9

For 90% we use t critical value since population standard deviation is not known.

T critical for 90% is 1.669

Margin of error = ± $1.669*\sqrt{\frac{3.7}{\sqrt{64} } } \\=0.7719$

b) Confidence interval 90%

= Mean±Marginof error

= $(29.128,30.672)$

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Professor Halen teaches a College Mathematics class. The scores on the midterm exam are normally distributed with a mean of 72.3

lbvjy [14]

Answer:

14.63% probability that a student scores between 82 and 90

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 72.3, \sigma = 8.9$