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Finding the Fourth Proportional to 819.95, 1,229.93 and 428.99

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Solution

The fourth proportional to 819.95, 1,229.93 and 428.99 is: 643.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.95 : 1,229.93 = 428.99 : x
  2. Step 2: Convert to fraction form
    819.95/1,229.93 = 428.99/x
  3. Step 3: Cross multiply
    819.95x = 1,229.93 × 428.99
  4. Step 4: Simplify right side
    819.95x = 527,619.38
  5. Step 5: Solve for x
    x = 527,619.38/819.95
  6. Step 6: Final answer
    x = 643.48

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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.