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Finding the Fourth Proportional to 781.08, 1,171.55 and 318.88

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Solution

The fourth proportional to 781.08, 1,171.55 and 318.88 is: 478.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.08 : 1,171.55 = 318.88 : x
  2. Step 2: Convert to fraction form
    781.08/1,171.55 = 318.88/x
  3. Step 3: Cross multiply
    781.08x = 1,171.55 × 318.88
  4. Step 4: Simplify right side
    781.08x = 373,576.41
  5. Step 5: Solve for x
    x = 373,576.41/781.08
  6. Step 6: Final answer
    x = 478.28

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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.