A study of 20 college students was conducted to see how many

A study of 20 college students was conducted to see how many adults would have low bone mineral density, even at a younger age. Investigators wish to know what is the probability of having a bone mineral density score less than 2 units below the unknown mean bone mineral density (BMD) of the general college population country-wide. The standard deviation was measured to be 6.

Solution

standard error = 6/sqrt( 20) = 1.3416

z value = -2/1.3416 = -1.49

p( z < -1.49) = 0.0681

The required answer = 0.07   ( two decimals)