SAT Math Multiple Choice Question 451: Answer and Explanation
1. In a market where approximately 44% of all book purchases are made online, customer reviews are extremely important from a sales and marketing perspective. Early reviews are most important, as they help or hinder a book's momentum in the marketplace. The frequency table shown above gives the first 20 customer ratings for a certain book sold online. What is the mean rating for this book?
- A. 3
- B. 3.4
- C. 3.7
- D. 4
Correct Answer: B
Category: Problem Solving and Data Analysis / Statistics and Probability
Strategic Advice: The mean rating means the average score given. To find the average, multiply each score by the number of times it occurs (the frequency). Then, add the results and divide by the total number of scores, 20.
Getting to the Answer: The sum of the ratings is (2 × 4) + (3 × 6) + (4 × 8) + (5 × 2) = 8 + 18 + 32 + 10 = 68.
Divide by the number of ratings to find that the mean is 68 ÷ 20 = 3.4.