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Finding the Fourth Proportional to 978.61, 1,350.40 and 553.21

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Solution

The fourth proportional to 978.61, 1,350.40 and 553.21 is: 763.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.61 : 1,350.40 = 553.21 : x
  2. Step 2: Convert to fraction form
    978.61/1,350.40 = 553.21/x
  3. Step 3: Cross multiply
    978.61x = 1,350.40 × 553.21
  4. Step 4: Simplify right side
    978.61x = 747,054.78
  5. Step 5: Solve for x
    x = 747,054.78/978.61
  6. Step 6: Final answer
    x = 763.38

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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.