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Finding the Fourth Proportional to 420.74, 627.92 and 409.80

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Solution

The fourth proportional to 420.74, 627.92 and 409.80 is: 611.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.74 : 627.92 = 409.80 : x
  2. Step 2: Convert to fraction form
    420.74/627.92 = 409.80/x
  3. Step 3: Cross multiply
    420.74x = 627.92 × 409.80
  4. Step 4: Simplify right side
    420.74x = 257,319.57
  5. Step 5: Solve for x
    x = 257,319.57/420.74
  6. Step 6: Final answer
    x = 611.60

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.