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Finding the Fourth Proportional to 820.40, 1,229.88 and 455.12

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Solution

The fourth proportional to 820.40, 1,229.88 and 455.12 is: 682.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.40 : 1,229.88 = 455.12 : x
  2. Step 2: Convert to fraction form
    820.40/1,229.88 = 455.12/x
  3. Step 3: Cross multiply
    820.40x = 1,229.88 × 455.12
  4. Step 4: Simplify right side
    820.40x = 559,742.99
  5. Step 5: Solve for x
    x = 559,742.99/820.40
  6. Step 6: Final answer
    x = 682.28

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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.