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Finding the Fourth Proportional to 781.56, 1,172.61 and 660.96

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Solution

The fourth proportional to 781.56, 1,172.61 and 660.96 is: 991.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.56 : 1,172.61 = 660.96 : x
  2. Step 2: Convert to fraction form
    781.56/1,172.61 = 660.96/x
  3. Step 3: Cross multiply
    781.56x = 1,172.61 × 660.96
  4. Step 4: Simplify right side
    781.56x = 775,048.31
  5. Step 5: Solve for x
    x = 775,048.31/781.56
  6. Step 6: Final answer
    x = 991.67

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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.