Kalino earned 85, 95, 93 and 80 points on the 4 tests, each worth 100 points, given so far this term. How many points must he earn on his test, also worth 100 points, to average 90 points for the 5 tests given this term?

Options

A. 87
B. 88
C. 90
D. 97

Answer

To find out how many points Kalino must earn on his fifth test to achieve an average of 90 points over five tests, we can follow these steps:

### Step 1: Calculate the total points needed for an average of 90
To find the total points needed for an average of 90 over 5 tests, we use the formula:

\[ \text{Total Points Needed} = \text{Average} \times \text{Number of Tests} \]

Substituting the values:

\[ \text{Total Points Needed} = 90 \times 5 = 450 \]

### Step 2: Calculate the total points earned from the first four tests
Next, we need to sum up the scores Kalino earned in the first four tests:

\[ \text{Total Points from 4 Tests} = 85 + 95 + 93 + 80 \]

Calculating this gives:

\[ \text{Total Points from 4 Tests} = 353 \]

### Step 3: Set up the equation to find the score needed on the fifth test
Let \( x \) be the score Kalino needs on the fifth test. The equation to find \( x \) is:

\[ \text{Total Points from 4 Tests} + x = \text{Total Points Needed} \]

Substituting the known values:

\[ 353 + x = 450 \]

### Step 4: Solve for \( x \)
To find \( x \), we rearrange the equation:

\[ x = 450 - 353 \]

Calculating this gives:

\[ x = 97 \]

### Conclusion
Kalino must earn **97 points** on his fifth test to achieve an average of 90 points across all five tests.

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