Step-by-step explanation:
Suppose we have a group of 10 light users and 10 heavy users. what is the probability that exactly 3 of the 20 users are hiv pos
1 answer:
Answer: The answer is 30%.
Step-by-step explanation: Given that there is a group of 10 light users and 10 heavy users. We are to find the probability that exactly 3 of the 20 users are HIV positive.
We have the following four possible cases -
(i) All 3 are light users.
(ii) 1 is a light user and 2 are heavy users.
(iii) 2 are light users and 1 is a heavy user.
(iv) All 3 are heavy user.
Since there is a 45% chance of a light user to be HIV positive and 55% chance of a heavy user to be HIV positive, so the required probability is given by
Thus, the probability is 30.
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Answer:
Step-by-step explanation:
Hello!
You have the math and writing SAT scores of twelve students.
There are two variables of interest X₁: Math SAT score of a student. and X₂: Writing the SAT score of a student.
These two variables aren't independent since both of them represent data corresponding to the same student, meaning, that the math and writing scores belong to the same students and not to two separate groups of students.
This is an example of paired samples, to make the statistical test you have to establish a third variable, this variable will be the difference between the other two:
Xd= X₁-X₂
Xd: "Difference between the Math and Writing SAT scores of a student.
This variable has a normal distribution Xd~N(μd;σd²)
a. Using a .05 level of significance and test for a difference between the population mean for the math scores and the population mean for the writing scores? Enter negative values as negative numbers. Round your answer to two decimal places.
The parameter of interest is μd is the population mean of the difference between the math and writing SAT scores of the students.
The hypotheses are:
H₀: μd=0
H₁: μd≠0
α: 0.05
The test statistic is a t-student for dependent samples and it's rejection region is two-tailed.
What is the p-value? Round your answer to four decimal places.
The p-value for this test is: 0.0394
The p-value is less than the level of significance, the decision is to reject the null hypothesis.
b. What is the point estimate of the difference between the mean scores for the two tests?
The sample mean for the variable "difference" is X[bar]d
You can calculate the point estimate of the sample mean of the variable Xd using two ways.
1) You calculate all the differences between the pairs of scores, add them and divide them by the sample size
X[bar]d= ∑di/n
∑di= 300
n=12
X[bar]d= 300/12= 25
2) You can calculate the sample mean for each variable and then calculate the difference between the two sample means
X[bar]₁= ∑X₁/n
∑X₁= 6168
X[bar]₁= 6168/12= 514
X[bar]₂= ∑X₂/n
∑X₂= 5868
X[bar]₂= 5868/12= 489
X[bar]d= X[bar]₁-X[bar]₂ = 514 - 489= 25
What are the estimates of the population mean scores for the two tests?
Math test X[bar]₁= 514
Writing test X[bar]₂= 489
Which test reports the higher mean score?
The Math test reports a higher mean score.
I hope it helps!
