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Finding the Fourth Proportional to 429.60, 647.76 and 424.20

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Solution

The fourth proportional to 429.60, 647.76 and 424.20 is: 639.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.60 : 647.76 = 424.20 : x
  2. Step 2: Convert to fraction form
    429.60/647.76 = 424.20/x
  3. Step 3: Cross multiply
    429.60x = 647.76 × 424.20
  4. Step 4: Simplify right side
    429.60x = 274,779.79
  5. Step 5: Solve for x
    x = 274,779.79/429.60
  6. Step 6: Final answer
    x = 639.62

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.