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Finding the Fourth Proportional to 813.16, 1,220.28 and 428.68

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Solution

The fourth proportional to 813.16, 1,220.28 and 428.68 is: 643.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.16 : 1,220.28 = 428.68 : x
  2. Step 2: Convert to fraction form
    813.16/1,220.28 = 428.68/x
  3. Step 3: Cross multiply
    813.16x = 1,220.28 × 428.68
  4. Step 4: Simplify right side
    813.16x = 523,109.63
  5. Step 5: Solve for x
    x = 523,109.63/813.16
  6. Step 6: Final answer
    x = 643.30

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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.