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Finding the Fourth Proportional to 312.87, 434.70 and 309

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Solution

The fourth proportional to 312.87, 434.70 and 309 is: 429.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.87 : 434.70 = 309 : x
  2. Step 2: Convert to fraction form
    312.87/434.70 = 309/x
  3. Step 3: Cross multiply
    312.87x = 434.70 × 309
  4. Step 4: Simplify right side
    312.87x = 134,322.30
  5. Step 5: Solve for x
    x = 134,322.30/312.87
  6. Step 6: Final answer
    x = 429.32

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.