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Finding the Fourth Proportional to 420.79, 631.19 and 128.29

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Solution

The fourth proportional to 420.79, 631.19 and 128.29 is: 192.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.79 : 631.19 = 128.29 : x
  2. Step 2: Convert to fraction form
    420.79/631.19 = 128.29/x
  3. Step 3: Cross multiply
    420.79x = 631.19 × 128.29
  4. Step 4: Simplify right side
    420.79x = 80,975.37
  5. Step 5: Solve for x
    x = 80,975.37/420.79
  6. Step 6: Final answer
    x = 192.44

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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.