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Finding the Fourth Proportional to 420.60, 630.90 and 400.80

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Solution

The fourth proportional to 420.60, 630.90 and 400.80 is: 601.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.60 : 630.90 = 400.80 : x
  2. Step 2: Convert to fraction form
    420.60/630.90 = 400.80/x
  3. Step 3: Cross multiply
    420.60x = 630.90 × 400.80
  4. Step 4: Simplify right side
    420.60x = 252,864.72
  5. Step 5: Solve for x
    x = 252,864.72/420.60
  6. Step 6: Final answer
    x = 601.20

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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.