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Finding the Fourth Proportional to 318.80, 478.20 and 87.69

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Solution

The fourth proportional to 318.80, 478.20 and 87.69 is: 131.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.80 : 478.20 = 87.69 : x
  2. Step 2: Convert to fraction form
    318.80/478.20 = 87.69/x
  3. Step 3: Cross multiply
    318.80x = 478.20 × 87.69
  4. Step 4: Simplify right side
    318.80x = 41,933.36
  5. Step 5: Solve for x
    x = 41,933.36/318.80
  6. Step 6: Final answer
    x = 131.54

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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.