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Finding the Fourth Proportional to 781.10, 1,171.43 and 261.11

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Solution

The fourth proportional to 781.10, 1,171.43 and 261.11 is: 391.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.10 : 1,171.43 = 261.11 : x
  2. Step 2: Convert to fraction form
    781.10/1,171.43 = 261.11/x
  3. Step 3: Cross multiply
    781.10x = 1,171.43 × 261.11
  4. Step 4: Simplify right side
    781.10x = 305,873.71
  5. Step 5: Solve for x
    x = 305,873.71/781.10
  6. Step 6: Final answer
    x = 391.60

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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.