A student scores 80, 90, and 70 in three subjects. If he wants an average of 85 after scoring in a fourth subject, what should he score?
Practice Questions
1 question
Q1
A student scores 80, 90, and 70 in three subjects. If he wants an average of 85 after scoring in a fourth subject, what should he score?
90
95
100
85
Total score needed for average of 85 = 4 * 85 = 340. Current total = 80 + 90 + 70 = 240. Required score = 340 - 240 = 100.
Questions & Step-by-step Solutions
1 item
Q
Q: A student scores 80, 90, and 70 in three subjects. If he wants an average of 85 after scoring in a fourth subject, what should he score?
Solution: Total score needed for average of 85 = 4 * 85 = 340. Current total = 80 + 90 + 70 = 240. Required score = 340 - 240 = 100.
Steps: 8
Step 1: Understand that the average score is calculated by adding all the scores together and then dividing by the number of subjects.
Step 2: The student has scores of 80, 90, and 70 in three subjects.
Step 3: Calculate the total score from the three subjects: 80 + 90 + 70.
Step 4: Add the scores: 80 + 90 = 170, then 170 + 70 = 240. So, the current total score is 240.
Step 5: The student wants an average of 85 after scoring in a fourth subject. To find the total score needed for this average, multiply the average (85) by the number of subjects (4): 4 * 85.
Step 6: Calculate 4 * 85, which equals 340. This is the total score needed for an average of 85.
Step 7: To find out what score the student needs in the fourth subject, subtract the current total score (240) from the total score needed (340): 340 - 240.
Step 8: Calculate 340 - 240, which equals 100. Therefore, the student needs to score 100 in the fourth subject.
