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Finding the Fourth Proportional to 978.76, 1,350.50 and 629.40

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Solution

The fourth proportional to 978.76, 1,350.50 and 629.40 is: 868.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.76 : 1,350.50 = 629.40 : x
  2. Step 2: Convert to fraction form
    978.76/1,350.50 = 629.40/x
  3. Step 3: Cross multiply
    978.76x = 1,350.50 × 629.40
  4. Step 4: Simplify right side
    978.76x = 850,004.70
  5. Step 5: Solve for x
    x = 850,004.70/978.76
  6. Step 6: Final answer
    x = 868.45

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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.