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Finding the Fourth Proportional to 928.90, 1,390.65 and 489.11

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Solution

The fourth proportional to 928.90, 1,390.65 and 489.11 is: 732.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.90 : 1,390.65 = 489.11 : x
  2. Step 2: Convert to fraction form
    928.90/1,390.65 = 489.11/x
  3. Step 3: Cross multiply
    928.90x = 1,390.65 × 489.11
  4. Step 4: Simplify right side
    928.90x = 680,177.25
  5. Step 5: Solve for x
    x = 680,177.25/928.90
  6. Step 6: Final answer
    x = 732.24

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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.