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Finding the Fourth Proportional to 809.90, 1,214.05 and 420.10

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Solution

The fourth proportional to 809.90, 1,214.05 and 420.10 is: 629.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.90 : 1,214.05 = 420.10 : x
  2. Step 2: Convert to fraction form
    809.90/1,214.05 = 420.10/x
  3. Step 3: Cross multiply
    809.90x = 1,214.05 × 420.10
  4. Step 4: Simplify right side
    809.90x = 510,022.41
  5. Step 5: Solve for x
    x = 510,022.41/809.90
  6. Step 6: Final answer
    x = 629.74

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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.