Adult Male Polar Bears Are Expected to Weigh, on Average

Multiple Choice

Adult male polar bears are expected to weigh, on average, 370 kg. A polar bear's primary source of food are seals and other marine animals, which they hunt from a platform of sea ice. Scientists are concerned that global warming is melting these platforms earlier in the year, reducing the time polar bears are able to hunt and forcing them inland without the necessary fat reserves built up to survive summer and fall. The US Geological Survey (USGS) conducted a study in the Southern Beaufort Sea to investigate whether climate change has appeared to negatively impact the weight of polar bears, on average. Eighty-three adult male polar bears were captured between March and May of the years 1990 and 2006 and their weights were recorded. The sample mean weight was 324.6 kg and the sample standard deviation was 88.3 kg.
-Does the confidence interval in question 45 provide statistically significant evidence that the true mean weight of adult male polar bears in the Southern Beaufort Sea is less than 370 kg?

A) No, since we only sampled 83 captured adult male polar bears and not the entire population.
B) No, since the entire confidence interval lies above zero.
C) Yes, since the sample mean of 324.6 kg is less than 370 kg.
D) Yes, since the entire confidence interval lies below 370 kg.