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Finding the Fourth Proportional to 821.70, 1,230.21 and 455.13

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Solution

The fourth proportional to 821.70, 1,230.21 and 455.13 is: 681.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.70 : 1,230.21 = 455.13 : x
  2. Step 2: Convert to fraction form
    821.70/1,230.21 = 455.13/x
  3. Step 3: Cross multiply
    821.70x = 1,230.21 × 455.13
  4. Step 4: Simplify right side
    821.70x = 559,905.48
  5. Step 5: Solve for x
    x = 559,905.48/821.70
  6. Step 6: Final answer
    x = 681.40

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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.