The Normal Distribution Curve Which Models, Distributions of Data in a Wide

Multiple Choice

The normal distribution curve which models, distributions of data in a wide range of applications, is given by the function where and and are constants called the standard deviation and the mean, respectively. Its graph is shown in the figure. In a survey, consumers were asked to rate a new toothpaste on a scale of 1-10. The resulting data are modeled by a normal distribution with and . The percentage of consumers who gave the toothpaste a score between a and b on the section is given by . Use a Riemann sum with n = 10 to estimate the percentage of customers who rated the toothpaste 4 or higher. (Use the range 3.5 to 10.5.)

A) 88%
B) 92%
C) 89%
D) 90%
E) 91%