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Finding the Fourth Proportional to 309.72, 429.36 and 299.64

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Solution

The fourth proportional to 309.72, 429.36 and 299.64 is: 415.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.72 : 429.36 = 299.64 : x
  2. Step 2: Convert to fraction form
    309.72/429.36 = 299.64/x
  3. Step 3: Cross multiply
    309.72x = 429.36 × 299.64
  4. Step 4: Simplify right side
    309.72x = 128,653.43
  5. Step 5: Solve for x
    x = 128,653.43/309.72
  6. Step 6: Final answer
    x = 415.39

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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.