The IQ scores for a random sample of subjects with low lead levels in their blood and another random sample of subjects with high lead levels in their blood were collected. The statistics are summarized in the accompanying table. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Complete parts (a) to (c) below. C Low Lead Level High Lead Level μ n X S ₁ 88 94.28536 15.97749 ₂ 22 87.33167 8.36493 D

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The IQ scores for a random sample of subjects with low
lead levels in their blood and another random sample of
subjects with high lead levels in their blood were collected.
The statistics are summarized in the accompanying table.
Assume that the two samples are independent simple
random samples selected from normally distributed
populations. Do not assume that the population standard
deviations are equal. Complete parts (a) to (c) below.
a. Use a 0.05 significance level to test the claim that the mean IQ score of people with low blood lead levels is higher
than the mean IQ score of people with high blood lead levels.
What are the null and alternative hypotheses? Assume that population 1 consists of subjects with low lead levels and
population 2 consists of subjects with high lead levels.
OA. Ho: H₁ H₂
M₂
H₁: M₁
OC. Ho: H₁1 H¹₂
H₁: H₁ H₂
The test statistic is
The P-value is
n
X
S
μ
Low Lead Level ₁1 88 94.28536 15.97749
High Lead Level ₂ 22 87.33167 8.36493
State the conclusion for the test.
(Round to two decimal places as needed.)
(Round to three decimal places as needed.)
B. Ho: H₁ H₂
H₁: H₁ H₂
D. Ho: ₁ = ₂
H₁: H₁ H₂
O A. Fail to reject the null hypothesis. There is not sufficient evidence to support the claim that subjects with low lead
levels have higher IQ scores.
B. Fail to reject the null hypothesis. There is sufficient evidence to support the claim that subjects with low lead
levels have higher IQ scores.
because the confidence interval contains
C. Reject the null hypothesis. There is sufficient evidence to support the claim that subjects with low lead levels
have higher IQ scores.
D. Reject the null hypothesis. There is not sufficient evidence to support the claim that subjects with low lead
levels have higher IQ scores.
b. Construct a confidence interval appropriate for the hypothesis test in part (a).
<H₁-H₂
(Round to one decimal place as needed.)
c. Does exposure to lead appear to have an effect on IQ scores?
Transcribed Image Text:The IQ scores for a random sample of subjects with low lead levels in their blood and another random sample of subjects with high lead levels in their blood were collected. The statistics are summarized in the accompanying table. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Complete parts (a) to (c) below. a. Use a 0.05 significance level to test the claim that the mean IQ score of people with low blood lead levels is higher than the mean IQ score of people with high blood lead levels. What are the null and alternative hypotheses? Assume that population 1 consists of subjects with low lead levels and population 2 consists of subjects with high lead levels. OA. Ho: H₁ H₂ M₂ H₁: M₁ OC. Ho: H₁1 H¹₂ H₁: H₁ H₂ The test statistic is The P-value is n X S μ Low Lead Level ₁1 88 94.28536 15.97749 High Lead Level ₂ 22 87.33167 8.36493 State the conclusion for the test. (Round to two decimal places as needed.) (Round to three decimal places as needed.) B. Ho: H₁ H₂ H₁: H₁ H₂ D. Ho: ₁ = ₂ H₁: H₁ H₂ O A. Fail to reject the null hypothesis. There is not sufficient evidence to support the claim that subjects with low lead levels have higher IQ scores. B. Fail to reject the null hypothesis. There is sufficient evidence to support the claim that subjects with low lead levels have higher IQ scores. because the confidence interval contains C. Reject the null hypothesis. There is sufficient evidence to support the claim that subjects with low lead levels have higher IQ scores. D. Reject the null hypothesis. There is not sufficient evidence to support the claim that subjects with low lead levels have higher IQ scores. b. Construct a confidence interval appropriate for the hypothesis test in part (a). <H₁-H₂ (Round to one decimal place as needed.) c. Does exposure to lead appear to have an effect on IQ scores?
Expert Solution
Step 1

We have given,

Let x1 be the IQ score for a random sample of low lead levels in their blood.

n1=88x¯1=94.28536, s1=15.97749

Let x2 be the IQ score for a random sample of high lead levels in their blood.

n2=22x¯2=87.33167, s2=8.36493

Assume that two samples are independent, and the random samples are normally distributed populations.

The level of significance is α=0.05.

 

 

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