A doctor at alocal hospital is interested in estimating the

A doctor at alocal hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 90% confident that her estimate is within 3 ounces of the true mean Assume that s = 8 ounces on carther studies. 4 19 5 20 What are the values of mu-_x and rho-_x for the sampling distribution of the sample mean shown mu-_x = 0.06, sigma -_x = 9 mu-_x = 9, sigma -_x = 0.18 mu-_x = 9, sigma -_x = 0.12 mu -_x = 9, sigma _x = 0.06 N = 17,000, n = 300, p = 0.8 mu _p = 0.8, sigma = 0.0970 mu_p = 0.8, sigma_p = 0.023 mu_p = 5, sigma+p = 0.023 mu_p = 240, n_p = 6.93 The following confidence interval is obtained for a population properation P: (0.298,0.322) Use these confidence interval limits to find the point estimate p. 0.312 0.322 0.298 0.310

Solution

1) Desired number of sample size

n = ( Z * s / E)²

Z = 1.65, s = 8 and E = 3

Thus, n = 19.36

thus, at least 20 people needed.

2)

Mean = median = mode = m_x = 9.00 for the distribution

Standard deviation = 9.06 - 9 = 9 - 8.94 = 0.06

4)

The mean of the distribution is the central value,

hence: mean of the distribution = (0.298 + 0.322 / 2)

= 31/100

= 0.310

3) for the sampling distribution,

mean of the sample = population mean = 0.8

variance of the sample = sqrt( 0.8 * 0.2 / 300)

= 0.023

hence, option B