The life spans of wild tribbles are normally distributed with a mean value of 1.8 years and a standard deviation of 0.8 year. Sketch the normal curve, and shade the portion of the graph showing tribble life spans of 1.0 to 1.8 years.

William Shatner (b 1931) played Captain James T. Kirk in the television series Star Trek (1966-1969). Captain Kirk and two fictional alien creatures called tribbles are shown here.