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Finding the Fourth Proportional to 828.60, 1,242.90 and 439.80

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Solution

The fourth proportional to 828.60, 1,242.90 and 439.80 is: 659.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    828.60 : 1,242.90 = 439.80 : x
  2. Step 2: Convert to fraction form
    828.60/1,242.90 = 439.80/x
  3. Step 3: Cross multiply
    828.60x = 1,242.90 × 439.80
  4. Step 4: Simplify right side
    828.60x = 546,627.42
  5. Step 5: Solve for x
    x = 546,627.42/828.60
  6. Step 6: Final answer
    x = 659.70

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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.