Final answer:
To find out what score Wendy got on her 7th quiz, we can use the formula for the mean (average) of a set of numbers. By finding the sum of her scores on all 7 quizzes and subtracting the sum of her scores on the first 6 quizzes, we can determine her 7th quiz score. Wendy got a score of 90% on her 7th quiz, which is option D) 88%.
Step-by-step explanation:
To solve this problem, we can use the formula for the mean (average) of a set of numbers. The formula is: mean = sum of all numbers / number of numbers. In this case, Wendy's mean score on 6 quizzes was 76%. This means that the sum of her scores on those 6 quizzes is 76% multiplied by 6. We can solve for the sum of her scores by multiplying both sides of the equation by 6: sum of scores = mean * number of quizzes = 76% * 6. Next, to find out what score Wendy got on her 7th quiz, we need to calculate the sum of her scores on all 7 quizzes. The mean score on all 7 quizzes is 78%. We can solve for the sum of her scores on all 7 quizzes by multiplying both sides of the equation by 7: sum of scores on 7 quizzes = mean * number of quizzes = 78% * 7. Finally, to find out what score Wendy got on her 7th quiz, we need to subtract the sum of her scores on the first 6 quizzes from the sum of her scores on all 7 quizzes: score on 7th quiz = sum of scores on 7 quizzes - sum of scores on 6 quizzes.
Now we can plug in the values and calculate:
Sum of scores on 6 quizzes = 76% * 6 = 0.76 * 6 = 4.56
Sum of scores on 7 quizzes = 78% * 7 = 0.78 * 7 = 5.46
Score on 7th quiz = 5.46 - 4.56 = 0.9 = 90%
Therefore, Wendy got a score of 90% on her 7th quiz, which is option D) 88%.