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Finding the Fourth Proportional to 780.74, 1,171.20 and 260.81

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Solution

The fourth proportional to 780.74, 1,171.20 and 260.81 is: 391.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.74 : 1,171.20 = 260.81 : x
  2. Step 2: Convert to fraction form
    780.74/1,171.20 = 260.81/x
  3. Step 3: Cross multiply
    780.74x = 1,171.20 × 260.81
  4. Step 4: Simplify right side
    780.74x = 305,459.21
  5. Step 5: Solve for x
    x = 305,459.21/780.74
  6. Step 6: Final answer
    x = 391.24

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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.