Final answer:
Val's margin of error for the average weight of cows can be calculated using the formula MoE = (1.96 × std dev) / √ n, where n is the sample size and std dev is the standard deviation. However, the standard deviation needs to be known, which is not provided in the question.
Step-by-step explanation:
The student is asking about finding the margin of error for an average weight estimation given by Val. When performing a sample survey to estimate a population parameter, such as an average or a mean, the margin of error gives a range in which the true population parameter is expected to fall with a certain level of confidence. To calculate Val's margin of error for the average weight of the cows, we need to know the standard deviation (std dev) of the weights of the 100 cows Val weighed. However, if the standard deviation is not given, it cannot be calculated from the information provided. Assuming that we somehow have the standard deviation, the formula to calculate the margin of error (MoE) is:
MoE = (1.96 × std dev) / √ n
Here, 'n' is the sample size which is 100 in Val's case. The calculation shows how sample size and standard deviation affect the precision of the estimate. A larger sample size or a smaller standard deviation results in a smaller margin of error, indicating a more precise estimate. The margin of error is usually added and subtracted from the sample mean to give a confidence interval for the population mean.