Content Area: Math

 

Index: 4.4B Grade 8 CPI 1

 

Standard: 4.4 - Data Analysis, Probability, and Discrete Mathematics

 

Strand: B - Probability

 

Cumulative Progress Indicator: 1 - The student will interpret probabilities as ratios, percents, and decimals.

 

Grade: 8

 

Sample Activities:

 

·        Students examine uses of probability expressed as percentages in such things as weather forecasting, risks in medical operations, and reporting the confidence interval of surveys.

 

·        Students work on problems like this one from the New Jersey State Department of Education's Mathematics Instructional Guide (p. 7-103):  A dart board is composed of three concentric circles with radii 2 cm, 10 cm, and 20 cm [as indicated in an accompanying diagram]. A grand prize is earned if a dart is thrown in the 2 cm circle (bulls-eye). Given that a person is blindfolded and throws a dart somewhere on the board, find the probability that the grand prize will be won when the first dart is thrown. Explain the process you used to solve the problem.

 

Sample Assessment Questions:

 

·        Weatherpersons predict tomorrow's weather based on what has happened in the past on the days following days just like today. During the past 50 years, there have been 380 days that have been just like today, and of those, 200 have been followed by a clear day. Which of the following is the approximate probability of a clear day tomorrow that would be given by a weatherperson using the prediction rule described in this problem? 

o       a) 13%

o       b) 34%

o       c) 53%

o       d) 66%

 

The correct answer is C.