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Finding the Fourth Proportional to 781.17, 1,171.51 and 261.05

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Solution

The fourth proportional to 781.17, 1,171.51 and 261.05 is: 391.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.17 : 1,171.51 = 261.05 : x
  2. Step 2: Convert to fraction form
    781.17/1,171.51 = 261.05/x
  3. Step 3: Cross multiply
    781.17x = 1,171.51 × 261.05
  4. Step 4: Simplify right side
    781.17x = 305,823.71
  5. Step 5: Solve for x
    x = 305,823.71/781.17
  6. Step 6: Final answer
    x = 391.49

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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.