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Finding the Fourth Proportional to 978.78, 1,468.19 and 285.45

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Solution

The fourth proportional to 978.78, 1,468.19 and 285.45 is: 428.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.78 : 1,468.19 = 285.45 : x
  2. Step 2: Convert to fraction form
    978.78/1,468.19 = 285.45/x
  3. Step 3: Cross multiply
    978.78x = 1,468.19 × 285.45
  4. Step 4: Simplify right side
    978.78x = 419,093.41
  5. Step 5: Solve for x
    x = 419,093.41/978.78
  6. Step 6: Final answer
    x = 428.18

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.