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Finding the Fourth Proportional to 312.81, 431.78 and 202.40

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Solution

The fourth proportional to 312.81, 431.78 and 202.40 is: 279.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.81 : 431.78 = 202.40 : x
  2. Step 2: Convert to fraction form
    312.81/431.78 = 202.40/x
  3. Step 3: Cross multiply
    312.81x = 431.78 × 202.40
  4. Step 4: Simplify right side
    312.81x = 87,392.27
  5. Step 5: Solve for x
    x = 87,392.27/312.81
  6. Step 6: Final answer
    x = 279.38

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.