A student has scores of 72, 78, and 87 on three government exams. What score does she need on a fourth exam to give her an average of 80 or better?
add up the total points. To average 80 on 4 exams, she need 4*80 = 320 points.
So, add up her scores so far; how many more does she need to get to 320?
To find the score the student needs on the fourth exam to achieve an average of 80 or better, we can use the formula for average:
Average = (Sum of scores) / (Number of scores)
Now, we know that the student has taken three exams and their respective scores are 72, 78, and 87. We also want to find the score on the fourth exam (let's call it X).
To calculate the average, we need to sum up the four scores and divide by 4:
80 = (72 + 78 + 87 + X) / 4
To isolate X, we can multiply both sides of the equation by 4:
320 = 72 + 78 + 87 + X
Combine the known scores:
320 = 237 + X
Now, subtract 237 from both sides:
320 - 237 = X
Simplifying the equation:
X = 83
Therefore, the student needs to score at least 83 on the fourth exam in order to achieve an average of 80 or better.