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Finding the Fourth Proportional to 312.95, 469.39 and 81.86

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Solution

The fourth proportional to 312.95, 469.39 and 81.86 is: 122.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.95 : 469.39 = 81.86 : x
  2. Step 2: Convert to fraction form
    312.95/469.39 = 81.86/x
  3. Step 3: Cross multiply
    312.95x = 469.39 × 81.86
  4. Step 4: Simplify right side
    312.95x = 38,421.51
  5. Step 5: Solve for x
    x = 38,421.51/312.95
  6. Step 6: Final answer
    x = 122.77

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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.