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Finding the Fourth Proportional to 780.72, 1,171.20 and 260.70

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Solution

The fourth proportional to 780.72, 1,171.20 and 260.70 is: 391.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.72 : 1,171.20 = 260.70 : x
  2. Step 2: Convert to fraction form
    780.72/1,171.20 = 260.70/x
  3. Step 3: Cross multiply
    780.72x = 1,171.20 × 260.70
  4. Step 4: Simplify right side
    780.72x = 305,331.84
  5. Step 5: Solve for x
    x = 305,331.84/780.72
  6. Step 6: Final answer
    x = 391.09

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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.