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Finding the Fourth Proportional to 691.79, 1,038.20 and 281.07

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Solution

The fourth proportional to 691.79, 1,038.20 and 281.07 is: 421.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.79 : 1,038.20 = 281.07 : x
  2. Step 2: Convert to fraction form
    691.79/1,038.20 = 281.07/x
  3. Step 3: Cross multiply
    691.79x = 1,038.20 × 281.07
  4. Step 4: Simplify right side
    691.79x = 291,805.47
  5. Step 5: Solve for x
    x = 291,805.47/691.79
  6. Step 6: Final answer
    x = 421.82

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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.