Harry has test grades of 85, 87, and 77 on his first three algebra tests. What must he get on his
fourth test to earn an average of at least 84?
85 + 87 + 77 = 249 > Henry's points to date.
The total points for four tests = 400
400 * 0.84 = 336
336 - 249 = 87
87
To find out what Harry must get on his fourth test to earn an average of at least 84, we can use the formula for average.
Average = (sum of all test scores) / (total number of tests)
Since Harry has already taken three tests, the sum of his scores so far is 85 + 87 + 77 = 249.
Now, let's calculate the average he needs to achieve:
84 = (249 + x) / 4
Here, x represents the score Harry needs to achieve on his fourth test.
To solve for x, we can multiply both sides of the equation by 4:
4 * 84 = 249 + x
336 = 249 + x
Next, subtract 249 from both sides of the equation:
336 - 249 = x
87 = x
Therefore, Harry must score at least 87 on his fourth test to earn an average of at least 84.