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Finding the Fourth Proportional to 807.90, 1,211.40 and 412.20

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Solution

The fourth proportional to 807.90, 1,211.40 and 412.20 is: 618.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    807.90 : 1,211.40 = 412.20 : x
  2. Step 2: Convert to fraction form
    807.90/1,211.40 = 412.20/x
  3. Step 3: Cross multiply
    807.90x = 1,211.40 × 412.20
  4. Step 4: Simplify right side
    807.90x = 499,339.08
  5. Step 5: Solve for x
    x = 499,339.08/807.90
  6. Step 6: Final answer
    x = 618.07

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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.