In an area of Russia records were kept on the relationship between the rainfall (in inches) and the yield of wheat (bushels per
acre). The data for a 9 year period is as follows: Rain Fall, x 13.1 11.4 16.0 15.1 21.4 12.9 9.6 18.2 18.6
Yield, y 48.5 44.2 56.8 80.4 47.2 29.9 74.0 74.0 76.8
The Equation of the line of least squares is given as ŷ = -9.12+ 4.38x. What would be the expected number of inches of rain if the yield is 60 bushels of wheat per acre?
(a) 11.62 (b) 64.74 c) 253.68 (d) 15.78 ANS: C Plug y= 60 and solve for x.
Your answers may vary slightly. 5.2 Normal Distributions: Finding Probabilities If you are given that a random variable Xhas a normal distribution, nding probabilities corresponds to nding the area between the standard normal curve and the x-axis, using the table of z-scores. The mean (expected value) and standard deviation ˙should be given