1 points Save Answer QUESTION 11 he animal colony at a hospital contains 24 male
ID: 3376293 • Letter: 1
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1 points Save Answer QUESTION 11 he animal colony at a hospital contains 24 male rats and 38 female rats. Of the 38 females, 28 are white and 10 spotted. Of the 24 males, 20 are white, and 4 are spotted. Suppose that you randomly select 1 rat from this colony. hat is the probability, as a proportion, of obtaining a female given the rat you have just sampled is spotted? Write your answer to TWO DECIMAL PLACES: X.X)X 3 points Save Answer QUESTION 12 Suppose we wish to compare the mean systolic blood pressure in two groups of patients using a two-sided t-test at the 5% level. We wish to detect a difference of 15 mmHg between groups of subjects allocated to each group at random with a 85% power. The population standard deviation is taken to be 25 mmHg. Assuming equal numbers in each group, how many subjects are required in each group? 1 points Save AnswerExplanation / Answer
(11)required probability=5/7=0.7143
P(female|spotted)=P(female and spotted)/P(spotted)=(10/62)/(14/62)=10/14=5/7
total=62, female and spotted=10, spotted=10 female+4 male=14
P(female and spotted)=10/62
P(spotted)=14/62
(12) number of subject requied in each gropu=25
alpha=0.05, beta=1-power=1-0.85=0.15,
Z(1-0.05/2)=1.96, Z(0.85)=1.04
ES=|µ1-µ2|/?=15/25=0.6
n=(Z(1-?/2)+Z(1-?))/ES)2 =((1.96+1.04)/0.6)2=5*5=25
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