3. The score of a test given as a percentage is given by S(t) = 50+ 14ln(t + 1), where t s equal to the number of hours a student studied for the test. How many hours should a student study in order to get a score of 90%?

Calculus: Early Transcendentals
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Chapter1: Functions And Models
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**Problem 13:**

The score of a test given as a percentage is represented by the function \( S(t) = 50 + 14 \ln(t + 1) \), where \( t \) is the number of hours a student studied for the test. The question asks: How many hours should a student study in order to achieve a score of 90%?

To solve this, set \( S(t) = 90 \) and solve for \( t \).

1. Start with the equation:  
   \[ 90 = 50 + 14 \ln(t + 1) \]

2. Subtract 50 from both sides:  
   \[ 40 = 14 \ln(t + 1) \]

3. Divide both sides by 14:  
   \[ \ln(t + 1) = \frac{40}{14} \]

4. Simplify:  
   \[ \ln(t + 1) = \frac{20}{7} \]

5. Exponentiate both sides to remove the logarithm:  
   \[ t + 1 = e^{\frac{20}{7}} \]

6. Solve for \( t \):  
   \[ t = e^{\frac{20}{7}} - 1 \]

After calculating \( e^{\frac{20}{7}} \), the result gives the number of hours required for a student to study to achieve a 90% score.
Transcribed Image Text:**Problem 13:** The score of a test given as a percentage is represented by the function \( S(t) = 50 + 14 \ln(t + 1) \), where \( t \) is the number of hours a student studied for the test. The question asks: How many hours should a student study in order to achieve a score of 90%? To solve this, set \( S(t) = 90 \) and solve for \( t \). 1. Start with the equation: \[ 90 = 50 + 14 \ln(t + 1) \] 2. Subtract 50 from both sides: \[ 40 = 14 \ln(t + 1) \] 3. Divide both sides by 14: \[ \ln(t + 1) = \frac{40}{14} \] 4. Simplify: \[ \ln(t + 1) = \frac{20}{7} \] 5. Exponentiate both sides to remove the logarithm: \[ t + 1 = e^{\frac{20}{7}} \] 6. Solve for \( t \): \[ t = e^{\frac{20}{7}} - 1 \] After calculating \( e^{\frac{20}{7}} \), the result gives the number of hours required for a student to study to achieve a 90% score.
Expert Solution
Step 1

given

s(t)=50+14ln(t+1)

here 

s(t)=score of test as a percentage

t=hours a student studied for the test

 

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