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Finding the Fourth Proportional to 669.66, 1,005.90 and 409.78

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Solution

The fourth proportional to 669.66, 1,005.90 and 409.78 is: 615.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    669.66 : 1,005.90 = 409.78 : x
  2. Step 2: Convert to fraction form
    669.66/1,005.90 = 409.78/x
  3. Step 3: Cross multiply
    669.66x = 1,005.90 × 409.78
  4. Step 4: Simplify right side
    669.66x = 412,197.70
  5. Step 5: Solve for x
    x = 412,197.70/669.66
  6. Step 6: Final answer
    x = 615.53

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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.