Ahypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. a sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. the null hypothesis is

The given sample is
x = [9.0, 7.3, 6.0, 8.8, 6.8, 8.4, 6.6]
The sample size is n = 7.
From the calculator, obtain
The sample mean is xb = 7.557
The sample std. deviation is s = 1.177

The expected population mean is μ = 6.6

Assume that the weights are normally distributed.
Calculate the z-score test statistic
z = (xb - mu)/(s/√n)
   = (7.557 - 6.6)/(1.177/√7)
   = 2.15

Select a confidence level of say, 95% so that the α-value if 0.05 for a 2-tailed test.

The null hypothesis is
H₀: xb = μ