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Finding the Fourth Proportional to 665.60, 998.40 and 419.20

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Solution

The fourth proportional to 665.60, 998.40 and 419.20 is: 628.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.60 : 998.40 = 419.20 : x
  2. Step 2: Convert to fraction form
    665.60/998.40 = 419.20/x
  3. Step 3: Cross multiply
    665.60x = 998.40 × 419.20
  4. Step 4: Simplify right side
    665.60x = 418,529.28
  5. Step 5: Solve for x
    x = 418,529.28/665.60
  6. Step 6: Final answer
    x = 628.80

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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.