# Project #78611 - Stats 107 Help

Here is a stemplot for ages at death (in years) of 20 dinosaur specimens, ranging from 2 years up to 28 years.

 0 22 0 57 1 0444 1 5567888 2 1224 2 8

(a) The mean age at death is 15 years and the standard deviation is 7 years. What percentage of the dinosaurs' ages were within 1 standard deviation of the mean? (Answer as a whole number.)
%

(b) What percentage of the dinosaurs' ages were within 2 standard deviations of the mean? (Answer as a whole number.)
%
(c) The units of standard deviation
s are years. What would be the units of variance s2?

yearssquared years    no units

(d) The shape of the stemplot is fairly normal, with only a bit of left-skewness. What would be the shape of the distribution for age at death of humans?

symmetric but not normalfairly normal    left-skewedright-skewed

(e) If paleontologists want to use the mean age, 15 years, to estimate the mean age at death of all dinosaurs, what is their main concern?

data productionstatistical inference    displaying and summarizing dataprobability

(f) Based on the information from this sample, which of these would be the most plausible value for mean age at death of all dinosaurs?

10 years14 years    18 years

Waist circumference of women in their twenties follows a somewhat normal distribution with mean 32 inches, standard deviation 5 inches.

(a) Use the 68-95-99.7 Rule to sketch a histogram for a large data set of women's waist circumferences, marking off the circumferences that are within 1, 2, and 3 standard deviations of the mean. What would be the seven key values marked off on the histogram from left to right? (Answer as whole numbers.)

 in (smallest value) in in in in in in (largest value)

(b) If instead of a histogram we sketched a normal curve for the waist circumferences of all women, what would change?

the shape would be smooththe vertical scale    the horizontal scaleall of thesenone of these

(c) Approximately what is the percentage of waists that are larger than 42 inches? (Round your answer to one decimal place.)
%

(d) The smallest 16% of waists are less than how many inches? (Answer as a whole number.)
in
(e) More precisely, the mean for women in their twenties is 32.2, and their median is 30.6. The mean for women in their eighties is 36.7, and their median is 36.4. Which age group has more skewness in the distribution of waist circumferences?

women in their twentieswomen in their eighties

(f) What type of skewness is it?

leftright

Suppose that weights of 1-year-old male children are fairly normally distributed with mean 27 pounds, standard deviation 2 pounds.

(a) If we use the 68-95-99.7 Rule to sketch a curve for this distribution, marking off the weights that are within 1, 2, and 3 standard deviations of the mean, report the 7 values that should be marked off in the sketch, in increasing order. (Answer as whole numbers.)

 (smallest value) (largest value)

(b) Find the
z-score for a male 1-year-old who weights 23 pounds. (Round your answer to two decimal places.)

(c) Find the weight (to the nearest pound) for a 1-year-old male whose
z-score is

−1.81.

lb

(d) What percentage of male 1-year-olds weigh less than
23 pounds? (Round your answer to one decimal place.)
%

It is reported that the proportion of college students at large public institutions who seek help at counseling centers is 0.10.

(a) If we test

H0: p = 0.10 vs. Ha: p  0.10,

which of these sample proportions would provide the most evidence against the null hypothesis, in favor of the alternative?

0.050.11    0.13

(b) If we test

H0: p = 0.10 vs. Ha: p  0.10,

which of these sample proportions would provide the least evidence against the null hypothesis?

0.050.11    0.13

(c) If we test

H0: p = 0.10 vs. Ha: p > 0.10,

which of these sample proportions would provide the most evidence against the null hypothesis, in favor of the alternative?

0.050.11    0.13

(d) If we test

H0: p = 0.10 vs. Ha: p > 0.10,

which of these sample proportions would provide the least evidence against the null hypothesis?

0.050.11    0.13

In a national poll of 1,706 Americans aged 45 and older conducted in 2004 for the AARP, 1,228 of respondents agreed with the statement, "Adults should be allowed to legally use marijuana for medical purposes if a physician recommends it." We want to use software to test if a majority (more than 0.5) of all Americans aged 45 and older support legalization of marijuana for medical purposes.

(a) First identify

H0 and Ha.

H0: μ = 0.72 vs. Ha: μ > 0.72

H0: μ = 0.50 vs. Ha: μ > 0.50

H0: μ = 0.72 vs. Ha: μ  0.72

H0: μ = 0.50 vs. Ha: μ  0.50

H0: p = 0.72 vs. Ha: p > 0.72

H0: p = 0.50 vs. Ha: p > 0.50

H0: p = 0.72 vs. Ha: p  0.72

H0: p = 0.50 vs. Ha: p  0.50

H0: pÌ‚ = 0.72 vs. Ha: pÌ‚ > 0.72

H0: pÌ‚ = 0.50 vs. Ha: pÌ‚ > 0.50

H0: pÌ‚ = 0.72 vs. Ha: pÌ‚  0.72

H0: pÌ‚ = 0.50 vs. Ha: pÌ‚  0.50

(b) According to the output, what is the sample proportion
pÌ‚? (Round your answer to two decimal places.)

(c) According to the output, what is the standardized sample proportion
z? (Round your answer to two decimal places.)

(d) According to the output, what is the
P-value? (Round your answer to three decimal places.)

(e) Does the poll provide convincing evidence that a majority of all Americans aged 45 and older support legalization of marijuana for medical purposes?

Yes, with strong evidence.Yes, but just barely.    No, not quite.No, not at all.

 Subject Mathematics Due By (Pacific Time) 08/07/2015 05:00 pm
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