Spring 2018: Math 227, Statistics Homework: HW 12.1 Score: 0 of 1 pt 12.1.25-T H

Question

Spring 2018: Math 227, Statistics Homework: HW 12.1 Score: 0 of 1 pt 12.1.25-T Hw Score: 0%, 0 of 4 o know whether mothers between the ages of 35 and 39 years give birth to a higher percentage of ow birth-weight babies. She randomly selected 350 births for which the mother was 35 to 30 years old and found 38 low-birh weight the expected number of low birth-weight births to 35-to 39-year old mothers What is the expected number of births to mothers 35 to 39 years old that are not low birth weigh? The expected number of The expacted number of births to mothers 35 to 39 years old that are not low birth weight is births to 35 to 39-yar-old mothers io births to 35- to 39-year-old mothers is Type integors or decimals.) 6 5

Explanation / Answer

Pr(Low birth weight) = 0.071

Total number of selected births = 350

The expected number of low birth weight = 350 * 0.071 = 24.85

expected number of not low birth weight = 350 * ( 1 - 0.071) = 325.15

Here sample proportion p^ = 38/350 = 0.1086

standard error of proportion = sqrt [0.071 * (1 - 0.071)/350] = 0.0137

Pr(p^ > 0.1086 ; 0.071 ; 0.0137)

Z = (0.1086 - 0.071)/ 0.0137 = 2.745

Pr(p^ > 0.1086 ; 0.071 ; 0.0137) = Pr(Z > 2.745) = 1 - Pr(Z < 2.745) = 1 - 0.9970 = 0.0030

p - value is less than 0.05 and so we reject the null hypothesis and say there is significant increase in low birth weight babies for 35 to 38 year old women.

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