Question
homen mula Ivanna spends \( \$ 14 \) each time she travels the toll roads. She started the month with \( \$ 224 \) in her toll road account. The amount, \( \mathbf{A} \) (in dollars), that she has left in the account after \( t \) trips on the toll roads is given by the following function. \[ A(t)=224-14 t \] Answer the following questions. (a) How many trips on the toll roads can Ivanna take until her account is empty? \( \square \) trips (b) How much money does she have left in the account after 9 trips on the toll roads? \[ 50 \]
Ask by Christensen Mcdonald. in the United States
Mar 16,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
**(a) Ivanna can take 16 trips until her account is empty.**
**(b) After 9 trips, she has \$98 left in her account.**
Solution
**(a) Determine the number of trips until the account is empty**
Ivanna’s account balance after \( t \) trips is given by
\[
A(t)=224-14t.
\]
To find when her account is empty, set \( A(t) \) equal to 0:
\[
224-14t=0.
\]
Now, solve for \( t \):
\[
14t=224 \quad \Longrightarrow \quad t=\frac{224}{14}=16.
\]
Thus, Ivanna can take **\( 16 \) trips** until her account is empty.
---
**(b) Calculate the amount remaining after 9 trips**
Substitute \( t=9 \) into the function:
\[
A(9)=224-14 \times 9.
\]
First, compute the cost for 9 trips:
\[
14 \times 9=126.
\]
Then, subtract this from the initial amount:
\[
A(9)=224-126=98.
\]
Thus, after 9 trips, Ivanna has **\( \$98 \)** left in her account.
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Bonus Knowledge
To find out how many trips Ivanna can take until her account is empty, we need to set \( A(t) \) to zero and solve for \( t \): \[ 0 = 224 - 14t \] Rearranging gives: \[ 14t = 224 \quad \Rightarrow \quad t = \frac{224}{14} = 16 \] So, Ivanna can take \( \boxed{16} \) trips before her account is empty. For part (b), we simply plug in \( t = 9 \) into the function \( A(t) \): \[ A(9) = 224 - 14 \times 9 = 224 - 126 = 98 \] Therefore, after 9 trips, she has \( \boxed{98} \) dollars left in her account.