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Finding the Fourth Proportional to 2,212.80, 3,319.20 and 978.90

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Solution

The fourth proportional to 2,212.80, 3,319.20 and 978.90 is: 1,468.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,212.80 : 3,319.20 = 978.90 : x
  2. Step 2: Convert to fraction form
    2,212.80/3,319.20 = 978.90/x
  3. Step 3: Cross multiply
    2,212.80x = 3,319.20 × 978.90
  4. Step 4: Simplify right side
    2,212.80x = 3,249,164.88
  5. Step 5: Solve for x
    x = 3,249,164.88/2,212.80
  6. Step 6: Final answer
    x = 1,468.35

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.