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Finding the Fourth Proportional to 689.20, 1,034.20 and 256.40

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Solution

The fourth proportional to 689.20, 1,034.20 and 256.40 is: 384.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.20 : 1,034.20 = 256.40 : x
  2. Step 2: Convert to fraction form
    689.20/1,034.20 = 256.40/x
  3. Step 3: Cross multiply
    689.20x = 1,034.20 × 256.40
  4. Step 4: Simplify right side
    689.20x = 265,168.88
  5. Step 5: Solve for x
    x = 265,168.88/689.20
  6. Step 6: Final answer
    x = 384.75

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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.