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Finding the Fourth Proportional to 420.32, 630.48 and 131.78

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Solution

The fourth proportional to 420.32, 630.48 and 131.78 is: 197.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.32 : 630.48 = 131.78 : x
  2. Step 2: Convert to fraction form
    420.32/630.48 = 131.78/x
  3. Step 3: Cross multiply
    420.32x = 630.48 × 131.78
  4. Step 4: Simplify right side
    420.32x = 83,084.65
  5. Step 5: Solve for x
    x = 83,084.65/420.32
  6. Step 6: Final answer
    x = 197.67

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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.