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Finding the Fourth Proportional to 781.11, 1,171.80 and 261.06

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Solution

The fourth proportional to 781.11, 1,171.80 and 261.06 is: 391.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.11 : 1,171.80 = 261.06 : x
  2. Step 2: Convert to fraction form
    781.11/1,171.80 = 261.06/x
  3. Step 3: Cross multiply
    781.11x = 1,171.80 × 261.06
  4. Step 4: Simplify right side
    781.11x = 305,908.89
  5. Step 5: Solve for x
    x = 305,908.89/781.11
  6. Step 6: Final answer
    x = 391.63

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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.