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Finding the Fourth Proportional to 1,405.65, 2,108.39 and 431.75

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Solution

The fourth proportional to 1,405.65, 2,108.39 and 431.75 is: 647.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,405.65 : 2,108.39 = 431.75 : x
  2. Step 2: Convert to fraction form
    1,405.65/2,108.39 = 431.75/x
  3. Step 3: Cross multiply
    1,405.65x = 2,108.39 × 431.75
  4. Step 4: Simplify right side
    1,405.65x = 910,297.38
  5. Step 5: Solve for x
    x = 910,297.38/1,405.65
  6. Step 6: Final answer
    x = 647.60

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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.