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Finding the Fourth Proportional to 1,089.20, 1,630.20 and 765.20

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Solution

The fourth proportional to 1,089.20, 1,630.20 and 765.20 is: 1,145.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,089.20 : 1,630.20 = 765.20 : x
  2. Step 2: Convert to fraction form
    1,089.20/1,630.20 = 765.20/x
  3. Step 3: Cross multiply
    1,089.20x = 1,630.20 × 765.20
  4. Step 4: Simplify right side
    1,089.20x = 1,247,429.04
  5. Step 5: Solve for x
    x = 1,247,429.04/1,089.20
  6. Step 6: Final answer
    x = 1,145.27

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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.