In Problems 13–18, find the indicated z-score. Be sure to draw a standard normal curve that depicts the solution.
Find the z-score such that the area under the standard normal curve to its right is 0.25.
Step 1 of 5) Find the z-score such that the area under the standard normal curve to its right is 0.25. This model gives the expected (or mean) value of HDL cholesterol for a specific BMI and total cholesterol for BMIs between 16 and 40 and total cholesterol levels between 130 mg>dL and 300 mg>dL. From this model we interpret the coefficients as follows: For a 1-unit increase in body mass index, high-density cholesterol is expected to decrease by 2 mg>dL. For a 1-unit increase in total cholesterol, high-density cholesterol is expected to increase 0.1 mg>dL. The following represent the expected HDL cholesterol of an individual with three different levels of BMI: x1 = 20: yn = 65 - 21202 + 0.1x2 = 25 + 0.1x2 x1 = 25: yn = 65 - 21252 + 0.1x2 = 15 + 0.1x2 x1 = 30: yn = 65 - 21302 + 0.1x2 = 5 + 0.1x2 Notice that each of these lines has the same slope, 0.1, but a different intercept.
