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Finding the Fourth Proportional to 978.86, 1,351.86 and 629.75

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Solution

The fourth proportional to 978.86, 1,351.86 and 629.75 is: 869.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.86 : 1,351.86 = 629.75 : x
  2. Step 2: Convert to fraction form
    978.86/1,351.86 = 629.75/x
  3. Step 3: Cross multiply
    978.86x = 1,351.86 × 629.75
  4. Step 4: Simplify right side
    978.86x = 851,333.84
  5. Step 5: Solve for x
    x = 851,333.84/978.86
  6. Step 6: Final answer
    x = 869.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.