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Finding the Fourth Proportional to 420.79, 630.21 and 406.20

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Solution

The fourth proportional to 420.79, 630.21 and 406.20 is: 608.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.79 : 630.21 = 406.20 : x
  2. Step 2: Convert to fraction form
    420.79/630.21 = 406.20/x
  3. Step 3: Cross multiply
    420.79x = 630.21 × 406.20
  4. Step 4: Simplify right side
    420.79x = 255,987.14
  5. Step 5: Solve for x
    x = 255,987.14/420.79
  6. Step 6: Final answer
    x = 608.35

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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.