Math Problem Statement

Let point P be the weighted average of points A(7,3) and B(–3,–10) , where point A weighs three times as much as point B. What are the coordinates of point P?

Multiple choice question.

A) (−2,−27/4)

B) (2,−7/2)

C) (9/2,−1/4)

D) (6,−1/3)

Solution

To find the coordinates of point PP, which is the weighted average of points A(7,3)A(7, 3) and B(3,10)B(-3, -10), with point AA weighing three times as much as point BB, we use the formula for the weighted average of two points:

P=(mAxA+mBxBmA+mB,mAyA+mByBmA+mB)P = \left( \frac{m_A \cdot x_A + m_B \cdot x_B}{m_A + m_B}, \frac{m_A \cdot y_A + m_B \cdot y_B}{m_A + m_B} \right)

Here, mA=3m_A = 3 and mB=1m_B = 1, since point AA weighs three times as much as point BB.

Let's calculate the coordinates of PP:

  1. x-coordinate of P:

xP=37+1(3)3+1=2134=184=92x_P = \frac{3 \cdot 7 + 1 \cdot (-3)}{3 + 1} = \frac{21 - 3}{4} = \frac{18}{4} = \frac{9}{2}

  1. y-coordinate of P:

yP=33+1(10)3+1=9104=14y_P = \frac{3 \cdot 3 + 1 \cdot (-10)}{3 + 1} = \frac{9 - 10}{4} = \frac{-1}{4}

So, the coordinates of point PP are (92,14)\left( \frac{9}{2}, -\frac{1}{4} \right).

The correct answer is:

C) (92,14)\left(\frac{9}{2}, -\frac{1}{4}\right)


Would you like further details or have any questions? Here are five related questions:

  1. How do you find the midpoint of two points?
  2. What is the general formula for the weighted average of three points?
  3. How can we find the centroid of a triangle given its vertices?
  4. What is the significance of the weights in calculating the weighted average?
  5. How do you apply the distance formula between two points?

Tip: Always double-check your calculations when dealing with fractions to avoid simple arithmetic errors.

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Math Problem Analysis

Mathematical Concepts

Weighted Average
Coordinate Geometry

Formulas

Weighted Average formula

Theorems

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Suitable Grade Level

Grades 9-12