A random sample of 500 people were classified by their ages into 3 age-groups: 29 years and younger, 30 to 64 years, and 65 years and older. Each person from the sample was surveyed about which of 4 major brands of cell phone they used. Their responses were compiled and displayed in a 3-by-4 contingency table. A researcher will use the data to investigate whether there is an association between cell phone brand and age-group. Which of the following is the appropriate test for the investigation?
A) A one-sample t-test for a population mean
B) A two-sample t-test for a difference between means
C) A chi-square goodness-of-fit test
D) A chi-square test of homogeneity
E) A chi-square test of independence
1 Answer
A company claims they produce their mixed bag of candies so that, of the candies in the bag, 20 percent are dark chocolate, 60 percent are milk chocolate, and 20 percent are white chocolate. In a random sample of candies of size 50, the counts are as follows: 6 dark, 32 milk, and 12 white. Assuming the conditions for inference are met, what is the test statistic for a chi-square goodness-of-fit test to investigate whether the distribution of the sample is consistent with the company’s claim?
A) χ2=62+322+122
B) χ2=102+302+102
C) χ2=(6−10)2+(32−30)2+(12−10)2
D) χ2=(6−10)210+(32−30)230+(12−10)210
E) χ2=(10−6)26+(30−32)232+(10−12)212
1 Answer
Students in a high school statistics class wanted to see if the distribution of the colors of a popular candy was different in the bags for different types of candies the company manufactures. The students purchased several large bags of regular candies, tropical-flavored candies, and sour-flavored candies. For each type of candy, the students took a random sample of 100 candies and recorded how many of each color (red, green, yellow, or blue) were in the sample. The students verified the conditions for inference and calculated a chi-square test statistic of 12.59 with a corresponding p-value of 0.05. Which of the following is the correct interpretation of the p-value in the context of the test?
A) The hypothesis test has a significance level of α=0.05.
B) There is a 5 percent chance that the distribution of colors is different for the different types of candies.
C) There is a 5 percent chance that the distribution of colors is the same for the different types of candies.
D) Assuming that the distribution of colors for the different types of candies is the same, there is a 5 percent chance of finding a test statistic of 12.59 or larger.
E) Assuming that the distribution of colors for the different types of candies is different, there is a 5 percent chance of finding a test statistic of 12.59 or larger.
1 Answer
How are the expected counts calculated when a chi-square goodness-of-fit test is conducted?
A) The expected counts are calculated by multiplying each proportion in the null hypothesis by 100.
B) The expected counts are calculated by multiplying each proportion in the alternative hypothesis by 100.
C) The values observed from the sample are the expected counts.
D) The expected counts are calculated by multiplying each proportion in the null hypothesis by the sample size.
E) The expected counts are calculated by multiplying each proportion in the alternative hypothesis by the sample size.
1 Answer
Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of the gray moths that emerged in 1980 was heterozygous?
a) 0%
b) 25%
c) 33%
d) 67%
e) 100%
1 Answer
Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what was the frequency of allele G in the gray moths that emerged in 1980?
a) 0.33
b) 0.50
c) 0.67
d) 0.75
e) 1.00
1 Answer
A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessive for the trait). What is the frequency of the recessive allele?
a) √0.75
b) 0.75
c) √0.50
d) √0.25
e) 0.25
1 Answer
Scientists are studying several populations of finches on neighboring islands in the South Pacific. Previous genetic analysis has shown that a single gene controls tail-feather length in the finch populations and that the allele for long tail feathers (L) is dominant to the allele for short tail feathers (l). On two separate islands, the scientists recorded the number of finches with long tail feathers and the number of finches with short tail feathers. The results are shown in the table below. If the two finch populations are each in Hardy-Weinberg equilibrium and are isolated from each other, then which of the following graphs correctly displays the relative genotype frequencies?
(Options not provided in the text)
1 Answer
All of the following are examples of prezygotic genetic isolating mechanisms EXCEPT:
a) Male fireflies of different species have differing flash patterns.
b) Three closely related orchid species flower on different days.
c) The progeny of a cross between two different lizard species fail to develop properly.
d) One species of snake lives in water and another is terrestrial.
e) Peeper frogs mate in April, and tree frogs mate in June.
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The appearance of a fertile, polyploid individual within a population of diploid organisms is a possible source of a new species. If this individual is capable of reproducing to form a new population, scientists would consider this to be an example of
a) allopatric speciation
b) sympatric speciation
c) polygenic inheritance
d) genetic drift
e) Hardy-Weinberg equilibrium
1 Answer
