Average Problems( Week 23 Evaluation) 1. There are 6 math exams during the semester. John has taken 5 exams so far and the scores were 81, 99, 91, 93, and 97. What will John need to score on his final math exam to have an average score of 89 for the semester? 2. There are 3 groups of numbers. The first group has 5 numbers with an average of 8. The second group has 6 numbers with an average of 9 and the third group has 9 numbers with an average of 18. What is the average of all these numbers? 3. The average of 15 numbers is 9. One of numbers was then changed to 3. The average of all the numbers becomes 6 now. What was the number before it was changed? 4. There are 5 numbers. Their average is 18. The average of the first 3 numbers is 14. The average of the last 3 numbers is 25. What is the 3rd number? 5. Consecutive numbers are natural numbers that follow in order, such as 1,2, 3, 4, 5,..., and so forth. Suppose the average of 21 consecutive numbers is 17. What is the average of the first 15 numbers in the set? 6. The average of 9 numbers is 20. Let the 1st number increases by 3, the 2nd number by 6, the 3rd number by 9, the 4th number by 12 ... and the 9th number by 27. What is the average of all the increased numbers? 7. The average score of a math exam is 95 in a class. The average score of the 18 girls in the class is 96 for the exam. The average score of the boys in the class is 93 for the exam. How many boys are there in the class? 8. There are 2 groups of numbers. The first group has 4 numbers with an average of 8. The second group has 2 numbers with an average of 7. What new number can be added to the 2 groups of numbers to make all 7 numbers have an average of 9? 9. There are a total of 8 exams for the chemistry class in the semester. Sofia got an average of 79 in the first 3 exams and 84 in the following 3 exams. What is the average she will need to score in the remaining exams in order to get an average of 80 for the semester? 10. What is the average of all three-digit numbers that are multiples of 18? |