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Finding the Fourth Proportional to 1,405, 2,107.82 and 431

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Solution

The fourth proportional to 1,405, 2,107.82 and 431 is: 646.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,405 : 2,107.82 = 431 : x
  2. Step 2: Convert to fraction form
    1,405/2,107.82 = 431/x
  3. Step 3: Cross multiply
    1,405x = 2,107.82 × 431
  4. Step 4: Simplify right side
    1,405x = 908,470.42
  5. Step 5: Solve for x
    x = 908,470.42/1,405
  6. Step 6: Final answer
    x = 646.60

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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.