How to find a missing value given the mean | Data and statistics | 6th grade | Khan Academy
TLDRThe video script presents a problem-solving scenario involving a babysitter who has kept a record of the ages of six children they have babysat recently. Unfortunately, one age is obscured by a blue ink spill. However, the babysitter remembers that they calculated the mean age of the children as four. Using this information, the script guides viewers through a step-by-step process to determine the missing age. By adding the known ages, dividing by the number of children, and then multiplying by the total number of ages, the babysitter deduces that the missing age is three. This engaging narrative not only solves the mystery but also illustrates the practical application of calculating the mean in everyday situations.
Takeaways
- ๐ The story begins with a babysitter who maintains a log of the children they babysit, including their ages.
- ๐ An issue arises when blue ink spills on the log, obscuring the age of one child.
- ๐ค Initially, the babysitter is worried about losing valuable information due to the ink spill.
- ๐งฎ The babysitter remembers calculating the mean age each time a new age was logged, which provides a clue to solving the problem.
- ๐ The mean age of the six children is known to be four, which is a key piece of information for finding the missing age.
- ๐ง The babysitter encourages viewers to pause and attempt to solve the problem on their own before revealing the solution.
- ๐ The mean is calculated by summing all ages and dividing by the number of children, which in this case is six.
- ๐ง By multiplying the mean by the number of children, the total sum of ages can be found, which helps in solving for the missing age.
- ๐ข The known ages are added together, and the sum is used to find the missing age by subtracting it from the total calculated with the mean.
- ๐ The missing age is determined to be three, which is found by subtracting the sum of known ages from the total calculated using the mean.
- ๐ The story illustrates the importance of keeping accurate records and the utility of mean calculation in solving problems when information is incomplete.
Q & A
What is the primary concern of the babysitter in the transcript?
-The babysitter is concerned about a blue ink spill that obscured the age of one of the children in their log.
How does the babysitter remember the ages of the children?
-The babysitter remembers the ages by keeping a log and recalculating the mean age each time a new age is added.
What is the mean age of the six children according to the babysitter's log?
-The mean age of the six children is four years old.
How does the babysitter use the mean to figure out the missing age?
-The babysitter uses the mean by setting up an equation where the total of all ages divided by the number of children equals the mean, and then solving for the missing age.
What is the total of the known ages of the five children?
-The total of the known ages of the five children is 21 (five plus two plus two plus four plus eight).
What mathematical operation is used to find the total of all ages?
-The babysitter multiplies the mean by the number of children to find the total of all ages.
What is the formula for calculating the mean age?
-The formula for calculating the mean age is the total sum of ages divided by the number of children.
What does the babysitter conclude is the missing age after solving the equation?
-The babysitter concludes that the missing age is three years old.
How does the babysitter verify the missing age?
-The babysitter verifies the missing age by subtracting the total of known ages from the product of the mean and the number of children.
What is the significance of the babysitter's method in solving for the missing age?
-The method demonstrates a practical application of mean calculation in real-life scenarios and shows how to deal with missing data points.
Why is it important to keep a log of the ages of children when babysitting?
-Keeping a log helps the babysitter to remember important details about the children they are caring for and can be useful for record-keeping and planning.
What advice does the video script give to the viewer?
-The video script encourages the viewer to pause and attempt to solve the problem independently before revealing the solution.
Outlines
๐ Solving for the Missing Age with Mean
The video script presents a problem-solving scenario where a babysitter has a log of children's ages but one age is obscured by ink. The babysitter recalls the mean age of the children, which is four. To find the missing age, the script guides the viewer through a mathematical process. It explains that the mean is calculated by summing all ages and dividing by the number of children. The script then demonstrates how to use the known mean and five of the six ages to calculate the missing age. By adding the known ages and dividing by the number of children, the script shows that the sum of the ages plus the missing age (represented as a question mark) equals the mean times the number of children. After simplification, it is determined that the missing age is three, completing the set of ages.
Mindmap
Keywords
๐กBabysitting business
๐กLog
๐กMean
๐กTotal of ages
๐กData points
๐กQuestion mark
๐กSolve
๐กBlue ink spill
๐ก
๐กMultiplication
๐กNumber of ages
๐กCancellation
๐กMissing number
Highlights
The babysitter keeps a log of the ages of children they babysit.
An age is obscured by a blue ink spill, creating a puzzle to solve.
The babysitter recalls the mean age of the children, which is four.
The mean age is used to recalculate the total age of all children.
The formula for calculating the mean is explained.
A method to find the missing age using the mean and known ages is proposed.
The total of known ages is calculated to be 21.
The mean age is multiplied by the number of children to find the total age.
The missing age is solved by setting up an equation with the mean and total known ages.
The missing age is found to be three by solving the equation.
The process of solving for the missing age is demonstrated step by step.
The importance of keeping accurate records is highlighted.
The practical application of mean in solving real-world problems is shown.
The video encourages viewers to pause and attempt the problem themselves.
A clear explanation of how to manipulate the mean formula to find a missing value is provided.
The solution to the puzzle is reached by substituting known values into the formula.
The video concludes with the exciting revelation of the missing age.
Transcripts
Browse More Related Video
Growth & Developmental Milestones | Pediatric Nursing Stages of Development
Why do we Need the Median? - Example | Don't Memorise
Using StatCrunch to perform hypothesis testing on two matched pair means of acting award ages
The Maths Prof: Ratio EXAM QUESTIONS
Applying the central limit theorem to find probability example 1
Logic Puzzle - Age equals sum of digits
5.0 / 5 (0 votes)
Thanks for rating: