Calculate earned run average
To calculate earned run average (ERA) of a baseball player, just use the following formula:
Earned run average = (Number of earned runs × 9)/(number of innings pitched)
The formula above applies only to pitchers and it is used to determine how good a pitcher is.
The formula is used to find out how many runs a pitcher allows in a baseball game.
The lower this average, the better the pitcher is at not allowing runs in the game
Pitchers usually practice a lot to keep this number as low as possible.
When computing this average, we usually round answers to two decimal places
Example #1:
A baseball player had the following performance:
Allowed 4 runs
15 innings pitched
Earned run average = (Number of earned runs × 9)/(number of innings pitched)
Earned run average = (4 × 9)/(15)
Earned run average = (36)/(15)
Earned run average = 2.4
After rounding the answer to two decimal places, we get earned run average = 2.40
Example #2:
A baseball player had the following performance:
Allowed 7 runs
34 innings pitched
Earned run average = (Number of earned runs × 9)/(number of innings pitched)
Earned run average = (7 × 9)/(34)
Earned run average = (63)/(34)
Earned run average = 1.852941
After rounding the answer to two decimal places, we get earned run average = 1.85
Example #3:
A baseball player had the following performance:
Allowed 5 runs
32 innings pitched
Earned run average = (Number of earned runs × 9)/(number of innings pitched)
Earned run average = (5 × 9)/(32)
Earned run average = (45)/(32)
Earned run average = 1.40625
After rounding the answer to two decimal places, we get earned run average = 1.41
If you are a baseball coach, you may want to choose the player in example #3 because his average is lower.
However, no one so far was able to get an earned run average of 1.41. The ERA by the player in example #2 is close to what top players of all time were able to meet

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