Ted needs an average of at least 70 on his three history tests. He has already scored 85 and 60 on two tests. What is the mimimum grade ted needs on his thirds test
x = result of the third test
After the third test, his average will be:
( 85 + 60 + x ) / 3
Ted needs an average of at least 70 on his three history tests means:
( 85 + 60 + x ) / 3 ≥ 70
( 145 + x ) / 3 ≥ 70
Multiply both sides by 3
145 + x ≥ 210
Subtract 145 to both sides
x ≥ 65
To find out the minimum grade Ted needs on his third test, we can use the formula for average:
Average = (Sum of all scores) / (Number of scores)
Since Ted needs an average of at least 70 on his three history tests, we can set up the equation:
70 = (85 + 60 + x) / 3
Here, x represents the score Ted needs on his third test.
To solve for x, we multiply both sides of the equation by 3:
70 * 3 = 85 + 60 + x
Simplifying the equation:
210 = 145 + x
To isolate x, we subtract 145 from both sides of the equation:
210 - 145 = 145 - 145 + x
65 = x
Therefore, Ted needs a minimum grade of 65 on his third test to achieve an average of at least 70.
To find out the minimum grade Ted needs on his third test, we need to determine the total score he must achieve on all three tests to have an average of at least 70.
Let's start by calculating the total score Ted has obtained so far.
On the first test, he scored 85.
On the second test, he scored 60.
Adding these scores together gives us: 85 + 60 = 145.
Now, let's determine the minimum score Ted needs on his third test to achieve an average of 70.
We know that the average of three tests should be at least 70, so the sum of all three test scores must be at least (70 * 3) = 210.
Since Ted has already scored 145 on the first two tests, we subtract this from the required total: 210 - 145 = 65.
Therefore, Ted needs at least a grade of 65 on his third test to achieve an average of at least 70.