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Finding the Fourth Proportional to 421.03, 631.42 and 128.48

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Solution

The fourth proportional to 421.03, 631.42 and 128.48 is: 192.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.03 : 631.42 = 128.48 : x
  2. Step 2: Convert to fraction form
    421.03/631.42 = 128.48/x
  3. Step 3: Cross multiply
    421.03x = 631.42 × 128.48
  4. Step 4: Simplify right side
    421.03x = 81,124.84
  5. Step 5: Solve for x
    x = 81,124.84/421.03
  6. Step 6: Final answer
    x = 192.68

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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.