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12345Finding more values

Exercises

Exercise 1

Study again the school doctor chart for girls. The P₅₀ line depicts the height of an average girl.

Use graphic interpolation to estimate the height of an average $15$ years and $3$ months old girl.

On her thirteenth birthday Marleen van Straaten is $164$ cm tall and on her fourteenth birthday she is $168$ cm tall. Predict how tall she will be at twenty by using the growth charts.

Why is extrapolation through both points not a good option in this situation?

Predict Marleen's weight at the age of twenty.

Exercise 2

The graph to the right contains the number of local phone calls per person per year and the number of postal packages per person per year in the United States.

After an initial decrease the graph of the number of local phone calls per person per year increases continually, except for two years. In which years does the graph not increase?

Did the total number of local phone calls not increase either during those years? Explain your answer.

In which periods did the number of postal packages per person per year decrease?

Use extrapolation to determine the number of local phone calls and the number of postal packages per person per year in de United States in the year 2000. Explain what you do.

Exercise 3

The table below shows the number of unemployed in a certain city. The numbers of unemployed have been rounded off to the nearest hundred.

time	mar'04	may'04	jul'04	sep'04	nov'04	jan'05	mar'05	may'05	jul'05	sep'05
number	10700	11400	11100	10300	10000	10700	11900	12600	12300	11500

Use this data to draw a graph.

How can you tell from this graph that there is a seasonal influence on unemployment?

Assume that this trend continues. Predict the number of unemployed in this city in January 2014.

How many people will be unemployed in March 2008 according to this trend?

Exercise 4

The Body Mass Index (BMI) indicates whether people of $16$ years and older have a normal weight (20 < BMI ≤ 25), are overweight (25 < BMI ≤ 30), obese (BMI > 30) or underweight (BMI ≤ 20). You can use these graphs to determine a person's BMI.

Estimate the BMI of an $18$ year old person, with a height of $1.90$ m and a weight of $90$ kg.

What is a normal weight for somebody older than $16$ years if this person is $1.80$ m tall? Give the upper and lower boundaries.

Sketch the graph for a BMI of $23$ .

Why are these BMI graphs valid only for people of $16$ years and over?

If you know somebody's length, the BMI only depends on this person's weight. Draw the graph of the BMI for a person with a length of $1.80$ m.

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