(c) No, because the percents are only of the examinations taken, not of the results of the girls and we also know any resukts of the boys.

Question

asked 2021-01-19

a) The statistic \(X^{2}\), that is used to estimate the variance \(S^{2}\) of a random sample, has a Chi-squared distribution.

b) The sum of the squares of k independent standard normal random variables has a Chi-squared distribution with k degrees of freedom.

c) The Chi-squared distribution is used in hypothesis testing and estimation.

d) The Chi-squared distribution is a particular case of the Gamma distribution.

e)All of the above.

asked 2020-11-26

An analysis of laboratory data collected with the goal of modeling the weight (in grams) of a bacterial culture after several hours of growth produced the least squares regression line \(\log(weight) = 0.25 + 0.61\)hours. Estimate the weight of the culture after 3 hours.

A) 0.32 g

B) 2.08 g

C) 8.0 g

D) 67.9 g

E) 120.2 g

asked 2021-02-06

At what age do babies learn to crawl? Does it take longer to learn in the winter when babies are often bundled in clothes that restrict their movement? Data were collected from parents who brought their babies into the University of Denver Infant Study Center to participate in one of a number of experiments between 1988 and 1991. Parents reported the birth month and the age at which their child was first able to creep or crawl a distance of 4 feet within 1 minute. The resulting data were grouped by month of birth: January, May, and September:

\(\begin{array}{c} & Crawling\ age \\ \hline Birth\ month & Mean & St.dev. & n \\ \hline January & 29.84 & 7.08 & 32 \\ May & 28.58 & 8.07 & 27 \\ September & 33.83 & 6.93 & 38\end{array}\)

Crawling age is given in weeks. Assume the data represent three independent simple random samples, one from each of the three populations consisting of babies born in that particular month, and that the populations of crawling ages have Normal distributions. A partial ANOVA table is given below

. \(\begin{array}{c}Source & Sum\ of\ squares & DF & Mean\ square\ F \\ \hline Groups & 505.26\\ Error & & &53.45\\ Total\end{array}\)

What are the degrees of freedom for the groups term?

asked 2021-03-07

\(\begin{array}{|c|c|} \hline Subject & (1) & (2) & (3) & (4) & (5) &(6) & (7) & (8) & (9) \\ \hline Black & 25.85 & 28.84 & 32.05 & 25.74 & 20.89 & 41.05 & 25.01 & 24.96 & 27.47 \\ \hline White & 18.28 & 20.84 & 22.96 & 19.68 & 19.509 & 24.98 & 16.61 & 16.07 & 24.59 \\ \hline \end{array}\)

Does the data indicate that the higher level of illumination yields a decrease of more than 5 sec in true average task completion time? Test the appropriate hypotheses using the P-value approach.