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Finding the Fourth Proportional to 978.72, 1,350.48 and 629.28

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Solution

The fourth proportional to 978.72, 1,350.48 and 629.28 is: 868.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.72 : 1,350.48 = 629.28 : x
  2. Step 2: Convert to fraction form
    978.72/1,350.48 = 629.28/x
  3. Step 3: Cross multiply
    978.72x = 1,350.48 × 629.28
  4. Step 4: Simplify right side
    978.72x = 849,830.05
  5. Step 5: Solve for x
    x = 849,830.05/978.72
  6. Step 6: Final answer
    x = 868.31

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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.