Asked by Bryan Torres on May 09, 2024

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Birth weights of babies born to full-term pregnancies follow roughly a Normal distribution.At Meadowbrook Hospital,the mean weight of babies born to full-term pregnancies is 7 pounds with a standard deviation of 14 ounces (1 pound = 16 ounces) . Dr.Watts (who works at Meadowbrook Hospital) has four deliveries (all for full-term pregnancies) coming up during the night.Assume that the birth weights of these four babies can be viewed as a simple random sample.What is the probability that all four babies will weigh more than 7.5 pounds?

A) 0.0065
B) 0.1265
C) 0.2839
D) 0.4858

Normal Distribution

A bell-shaped frequency distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean.

Standard Deviation

A statistic that measures the dispersion or spread of a set of data points relative to its mean.

Mean

The average of a set of numbers, calculated by dividing the sum of these numbers by the count of the numbers.

  • Assess probabilities by applying the criteria of normal distribution.
  • Learn about the essence of simple random sampling and its implications for the assessment of probabilities.
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dominique villarrealMay 14, 2024
Final Answer :
A
Explanation :
We need to first standardize the birth weight using the formula: z = (x - μ) / σ , where x is the birth weight, μ is the mean birth weight (in this case, 7 pounds = 112 ounces), and σ is the standard deviation (14 ounces). Therefore, z = (120 - 112) / 14 = 0.571. We then use a Normal distribution table (or calculator) to find the probability that a single baby weighs more than 7.5 pounds (i.e., a z-score of 0.3125). This probability is approximately 0.3849. Since each delivery is assumed to be independent, the probability that all four babies weigh more than 7.5 pounds is obtained by multiplying the probabilities together: P(all four > 7.5 pounds) = 0.3849^4 = 0.0065 (rounded to four decimal places). Therefore, the answer is A.