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Finding the Fourth Proportional to 978.72, 1,350.69 and 553.45

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Solution

The fourth proportional to 978.72, 1,350.69 and 553.45 is: 763.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.72 : 1,350.69 = 553.45 : x
  2. Step 2: Convert to fraction form
    978.72/1,350.69 = 553.45/x
  3. Step 3: Cross multiply
    978.72x = 1,350.69 × 553.45
  4. Step 4: Simplify right side
    978.72x = 747,539.57
  5. Step 5: Solve for x
    x = 747,539.57/978.72
  6. Step 6: Final answer
    x = 763.80

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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.