AP CALCULUS AB 2022 Exam Full Solution FRQ#1d

Weily Lin
4 May 202304:12
EducationalLearning
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TLDRThe video script discusses the formation of a line at a toll plaza and the maximum capacity of vehicles it can handle per hour. It is established that 400 cars per hour is the maximum rate, and when the rate exceeds this, a line forms. The script describes a method to determine when the line begins to form by graphing the function 'a of x minus 400', which reveals that the line starts forming at 1.469 hours. The line continues to accumulate until 3.598 hours, after which the rate drops below 400 and the line begins to diminish. To find the maximum number of vehicles in line at the toll plaza, the area above the curve of 'a of x minus 400' between 1.469 and 3.598 hours is calculated. The integral of this function within these bounds yields an area representing the maximum number of cars, which is approximately 71.25, rounded to the nearest whole number, 71 cars.

Takeaways
  • 🚦 The toll plaza has a maximum capacity of 400 cars per hour, beyond which a line begins to form.
  • πŸ“ˆ The graph of 'a of x minus 400' helps determine when the number of cars exceeds the toll plaza's capacity.
  • ⏱️ The line begins to form at approximately 1.469 hours, as calculated from the graph.
  • πŸš— The line continues to accumulate from 1.469 hours until 3.598 hours, indicating a period of congestion.
  • πŸ“Š After 3.598 hours, the rate 'a' drops below 400, suggesting the line will start to diminish as cars are processed.
  • πŸ” The area above the curve of 'a of x minus 400' represents the total number of backed-up cars.
  • πŸ“‰ The maximum number of cars in line occurs between 1.469 and 3.598 hours when the rate exceeds capacity.
  • βœ… The integral of 'a of x minus 400' from 1.469 to 3.598 hours yields an area of 72 or 71.25 cars.
  • πŸ”’ The greatest number of cars in line at the toll plaza, rounded to the nearest whole number, is 71 cars.
  • πŸ“ The justification is based on the condition that 'a of x minus 400' is greater than zero, indicating cars are lining up.
  • 🚧 The time intervals considered for the maximum number of cars in line are from 1.469 to 4 hours.
Q & A
  • What does the number 400 represent in the context of the toll plaza?

    -The number 400 represents the maximum rate or capacity of the toll plaza in terms of the number of cars that can be processed per hour.

  • What happens when the rate of cars (a of T) exceeds 400 cars per hour?

    -When the rate of cars exceeds 400 cars per hour, a line begins to form at the toll plaza as the number of cars arriving is greater than the toll plaza's capacity to process them.

  • What is the time at which the line begins to form (a of X)?

    -The line begins to form at approximately 1.469 hours, which is when the rate of cars (a of X) first exceeds the toll plaza's capacity of 400 cars per hour.

  • What is the time interval during which the line continues to accumulate?

    -The line continues to accumulate from 1.469 hours to 3.598 hours, during which the rate of cars (a of X) remains above 400 cars per hour.

  • What happens after 3.598 hours?

    -After 3.598 hours, the rate of cars (a of X) drops below 400 cars per hour, allowing the toll plaza to process all cars and the line to diminish.

  • How is the number of vehicles in the line for time T greater than T calculated?

    -The number of vehicles in the line for time T greater than T is calculated by integrating the function n of T from a to T, where a is the time at which the line begins to form.

  • What does the integral of a of X minus 400 represent?

    -The integral of a of X minus 400 represents the total number of cars that have backed up at the toll plaza during the time interval when the rate of cars exceeds the toll plaza's capacity.

  • What is the maximum number of cars that can be backed up at the toll plaza?

    -The maximum number of cars that can be backed up at the toll plaza is approximately 71.25, which is obtained by integrating the function from 1.469 hours to 3.598 hours and rounding to the nearest whole number.

  • Why is the area above the curve significant in this context?

    -The area above the curve is significant because it represents the total number of cars that have accumulated in the line at the toll plaza during the period when the rate of cars exceeds the toll plaza's capacity.

  • What is the justification for choosing 71 as the greatest number of cars in the line?

    -The justification for choosing 71 as the greatest number of cars in the line is based on the integration of the function from 1.469 hours to 3.598 hours, which yields an area of 71.25 cars, and rounding this value to the nearest whole number.

  • How does the toll plaza manage to reduce the line after 3.598 hours?

    -After 3.598 hours, the toll plaza is able to reduce the line because the rate of cars (a of X) falls below 400 cars per hour, allowing the toll plaza to process cars at a rate that matches or exceeds the arrival rate.

  • What is the significance of the time interval between 1.469 hours and 3.598 hours?

    -The time interval between 1.469 hours and 3.598 hours is significant because it is the period during which the most number of cars are backing up at the toll plaza due to the rate of cars exceeding the toll plaza's capacity.

Outlines
00:00
🚦 Understanding Toll Plaza Capacity and Line Formation

The first paragraph explains the dynamics of a toll plaza's operation. It states that a line forms when the arrival rate 'a of T' exceeds 400 cars per hour, which is the maximum capacity. The speaker has graphed 'avex minus 400' to determine when the arrival rate equals 400, finding it to be at 1.469 hours. The time when the line continues to accumulate, or 'a is above 400', is from 1.469 to 3.598 hours. After 3.598 hours, the arrival rate drops below 400, and the line starts to diminish. The task is to find the greatest number of vehicles in line at the toll plaza during the time intervals. The justification is based on the condition that cars line up when 'a of x minus 400' is greater than zero, which occurs between 1.469 and 3.598 hours. By integrating the function 'avex minus 400' over these bounds, the area representing the maximum number of cars backed up is calculated to be 71.25, which is rounded to 71 cars as the nearest whole number.

Mindmap
Keywords
πŸ’‘Toll Plaza
A toll plaza is a location where fees are collected from vehicles for the use of a particular stretch of road or a bridge. In the context of the video, it represents the point where cars are being processed and where congestion occurs when the rate of incoming traffic exceeds the toll plaza's capacity.
πŸ’‘Rate (a of T)
The rate, denoted as 'a of T' in the script, refers to the number of cars arriving at the toll plaza per hour. It is a critical parameter in determining whether a queue will form. When the rate exceeds the toll plaza's capacity, congestion begins.
πŸ’‘Capacity
Capacity, in this context, is the maximum number of cars that the toll plaza can process in an hour, which is given as 400 cars per hour. It is a threshold that, when exceeded, leads to the formation of a queue.
πŸ’‘Accumulating
Accumulating refers to the process of a growing number of vehicles queuing up at the toll plaza when the rate of incoming cars is higher than the toll plaza's capacity to process them. This is a key concept as it leads to the formation of the line of vehicles.
πŸ’‘Time Interval
A time interval in the script refers to the specific duration during which the number of cars at the toll plaza is being observed. The intervals mentioned are from 'a' to 'T', where 'a' is when the line begins to form, and 'T' is a later time when the situation is analyzed.
πŸ’‘Integration
Integration is a mathematical concept used to calculate the area under a curve between two points, which in this video represents the total number of cars that have accumulated in the queue during a given time interval. It is used to find the maximum number of cars in line at the toll plaza.
πŸ’‘Queue
A queue in this context is a line of vehicles waiting to pass through the toll plaza. The formation of the queue is a direct result of the toll plaza's capacity being exceeded by the incoming rate of cars.
πŸ’‘Back Up
Back up refers to the situation where the flow of vehicles is obstructed, leading to a build-up of cars at the toll plaza. This is a consequence of the rate of cars arriving being greater than the toll plaza's capacity to process them.
πŸ’‘
πŸ’‘Graph
A graph in the video is a visual representation used to determine when the rate of cars (a of X) equals or exceeds the toll plaza's capacity. It helps in identifying the time intervals where congestion occurs.
πŸ’‘Area Above the Curve
The area above the curve on the graph represents the excess number of cars that have arrived compared to the toll plaza's capacity during a specific time interval. This excess is what causes the queue to form and is used to calculate the maximum queue length.
πŸ’‘Maximum Number of Cars
The maximum number of cars refers to the greatest number of vehicles that have queued up at the toll plaza at any point in time. In the video, it is determined by integrating the rate of arrival above the toll plaza's capacity over the time interval where the queue forms.
πŸ’‘Time 'a'
Time 'a' is the specific point in time when the rate of cars (a of X) begins to exceed the toll plaza's capacity of 400 cars per hour, leading to the formation of a queue. It is a key parameter in identifying the start of the congestion.
πŸ’‘Time 'T'
Time 'T' is the upper limit of the time interval being considered for the analysis of the queue at the toll plaza. It is used in conjunction with time 'a' to determine the duration of the queue formation and the maximum number of cars in line.
Highlights

The toll plaza has a maximum capacity of 400 cars per hour.

A line begins to form when the rate of cars exceeds 400 per hour.

The time 'a' at which the line begins to form is crucial to understanding the backlog.

Graphical analysis is used to determine when 'a of X' passes 400.

The time 'a' is found to be 4.1.469 hours when the line begins.

The line continues to accumulate from 1.6469 hours to 3.598 hours.

After 3.598 hours, the rate 'a' drops below 400, reducing the backlog.

The integral of 'a of x minus 400' from 1.6469 to 3.598 hours represents the total backlog.

The area above the curve signifies the maximum number of cars backed up.

The integral calculation results in 72 or 71.25 cars as the maximum number in the line.

The greatest number of cars in the line at toll plaza is approximately 71, rounded to the nearest whole number.

The justification for the maximum number of cars is based on the condition 'a of x minus 400' being greater than zero.

The time interval for the maximum line-up is between 1.469 and 3.598 hours.

The process of line formation and dissipation is analyzed using mathematical integration.

The study provides a practical application of mathematical modeling to real-world traffic management.

The methodology can be applied to optimize toll plaza operations and reduce congestion.

The analysis assumes a continuous flow of cars and does not account for external variables.

The model could be refined with more data on traffic patterns and car arrival rates.

Transcripts
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