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.
-Are validity conditions met in order to use theory-based methods?

A) Yes, since there are at least 10 successes and 10 failures.
B) Yes, since the sample distribution is approximately symmetric.
C) Yes, since the sample size is greater than 20 and the sample distribution is not strongly skewed.
D) We cannot determine whether validity conditions are met with the information given.