Tree-ring dates were used extensively in archaeological studies at Burnt Mesa Pueblo. Suppose at one site on the mesa, tree-ring dates (for many samples) gave a mean date of 1 = year 1275 with standard deviation 1 = 36 years. At a second, removed site, the tree-ring dates gave a mean of 2 = year 1121 with standard deviation 2 = 44 years. Assume that both sites had dates that were approximately normally distributed. In the first area, an object was found and dated as x1 = year 1255. In the second area, another object was found and dated as x2 = year 1238.
The Standard Normal Distribution ( = 0, = 1)A graph with a bell-shaped, continuous, and symmetric curve above the horizontal axis labeled z is given.
There are 7 equally spaced labels on the axis; from left to right they are: −3, −2, −1, 0, 1, 2, and 3.
The curve enters the viewing window just above the axis at −3, reaches a peak at 0, and exits the viewing window just above the axis at 3.
There are 6 unlabeled regions under the curve and above the axis.
68% of the area under the curve lies between −1 and 1.
95% of the area under the curve lies between −2 and 2.
99.7% of the area under the curve lies between −3 and 3.
(a)
Convert x1 to a z value, and locate the value under the standard normal curve of the figure above. (Round your answers to two decimal places.)
z1 =
-0.56
Correct: Your answer is correct.
Convert x2 to a z value, and locate the value under the standard normal curve of the figure above. (Round your answers to two decimal places.)
z2 =
