Unfortunately, arsenic occurs naturally in some ground watert. A mean arsenic level of u8.0 parts per bilion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basts for arsenic. A random sample of 41 tests gave a sample mean of x=7.2 ppb arsenic, with s= 2.0 ppb. Does this information indicate that the mean level of arsenic in this well is less than pob? Use a0.01. (a) what is the level of significance? State the null and altemate hypotheses. O Hgi H=8 ppb; H H>8 ppb O Moi <8 ppb; H ppb O Hgi 4>8 ppb; HH-8 ppb O Ha: H =8 ppb; H u-8 ppb O Hgi H ppb; H <8 ppb (b) what sampling distribution will you use? Explain the rationale for your cholce of sampling distribution. O The standard normal, since the sample stze is large and ais unknown. O The standard normal, since the sample size is large and os known. O The Student's t, since the sample stze is large and os known, O The Student's t, unce the sample stze is large and os unknown. What is the value of the sample test statistic? (Round your answer to three deamal places) (c) Estimate the Pvalue. OPvalue 0.250 O 0.125

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Unfortunately, arsenic occurs naturally in some ground watert. A mean arsenic level of u 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basts for arsenic. A random sample of 41 tests gave a
sample mean of x = 7.2 ppb arsenic, with s = 2.0 ppb. Does this information Indicate that the mean level of arsenic in this well is less than 8 ppb? Use a = 0.01.
(a) What is the level of significance?
State the null and alternate hypotheses.
O Ho: H = 8 ppb; H: u > 8 ppb
O Ho: H<8 ppb; H: H=8 ppb
O Ho: 4 > 8 ppb; H: u = 8 ppb
O Hạ: H = 8 ppb; H: u -8 ppb
O Hai H = 8 ppb; H: u <8 ppb
(b) what sampling distribution will you use? Explain the rationale for your choice of sampling distribution.
O The standard normal, since the sample size is large and o is unknown.
O The standard normal, since the sample size is large and o is known.
O The Student's t, since the sample size is large and o is known.
O The Student's t, since the sample size is large and ois unknown.
What is the value of the sample test statistic? (Round your answer to three decimal places.)
(c) Estimate the P-value.
O P-value > 0.250
O 0.125 < P-value < 0.250
O 0.050 < P-value <0.125
O 0.025 < P.value < 0.050
O 0.005 < P-value <0,025
O P-value < 0.005
Sketch the sampling distribution and show the area corresponding to the Pvalue.
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Transcribed Image Text:b SPS Programs S n Uhline Locker: Virtu. E Untitled document -. G kji - Google Search I Spanish Unfortunately, arsenic occurs naturally in some ground watert. A mean arsenic level of u 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basts for arsenic. A random sample of 41 tests gave a sample mean of x = 7.2 ppb arsenic, with s = 2.0 ppb. Does this information Indicate that the mean level of arsenic in this well is less than 8 ppb? Use a = 0.01. (a) What is the level of significance? State the null and alternate hypotheses. O Ho: H = 8 ppb; H: u > 8 ppb O Ho: H<8 ppb; H: H=8 ppb O Ho: 4 > 8 ppb; H: u = 8 ppb O Hạ: H = 8 ppb; H: u -8 ppb O Hai H = 8 ppb; H: u <8 ppb (b) what sampling distribution will you use? Explain the rationale for your choice of sampling distribution. O The standard normal, since the sample size is large and o is unknown. O The standard normal, since the sample size is large and o is known. O The Student's t, since the sample size is large and o is known. O The Student's t, since the sample size is large and ois unknown. What is the value of the sample test statistic? (Round your answer to three decimal places.) (c) Estimate the P-value. O P-value > 0.250 O 0.125 < P-value < 0.250 O 0.050 < P-value <0.125 O 0.025 < P.value < 0.050 O 0.005 < P-value <0,025 O P-value < 0.005 Sketch the sampling distribution and show the area corresponding to the Pvalue. us O9I 8:29 hp esc -> C' #3 $4 backspace %3D 8. 9. 1 3 4 5.
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