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Finding the Fourth Proportional to 821.12, 1,132.80 and 489.02

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Solution

The fourth proportional to 821.12, 1,132.80 and 489.02 is: 674.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.12 : 1,132.80 = 489.02 : x
  2. Step 2: Convert to fraction form
    821.12/1,132.80 = 489.02/x
  3. Step 3: Cross multiply
    821.12x = 1,132.80 × 489.02
  4. Step 4: Simplify right side
    821.12x = 553,961.86
  5. Step 5: Solve for x
    x = 553,961.86/821.12
  6. Step 6: Final answer
    x = 674.64

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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.