Final answer:
Sonja scored 70% on her 40 question test by answering 28 questions correctly. The probability of a student randomly guessing answers on a 10-question true-false quiz and getting at least 7 correct (70%) would require computing the binomial probabilities for each possible outcome from 7 to 10 correct answers.
Step-by-step explanation:
The question is about calculating the percentage score Sonja got on her test. She answered 28 questions correctly out of 40 questions. To find the percentage, you would perform the following calculation: (Number of Correct Answers ÷ Total Number of Questions) × 100. So for Sonja's score, it would be (28 ÷ 40) × 100, which equals 70%. Thus, the correct answer is B) 70%.
Probability of passing with at least 70 percent on a true-false quiz is an interesting concept in probability. If a student guesses randomly on each of the 10 questions, to pass with at least 70%, they would need to get at least 7 questions correct. Because each question has two possible answers (true or false), the probability of getting each question correct by guessing is ½ or 50%. To find the specific probability of getting 7 or more correct would involve calculating the binomial probability for 7, 8, 9, and 10 correct answers and summing those probabilities.