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Finding the Fourth Proportional to 421.03, 631.45 and 128.45

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Solution

The fourth proportional to 421.03, 631.45 and 128.45 is: 192.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.03 : 631.45 = 128.45 : x
  2. Step 2: Convert to fraction form
    421.03/631.45 = 128.45/x
  3. Step 3: Cross multiply
    421.03x = 631.45 × 128.45
  4. Step 4: Simplify right side
    421.03x = 81,110.77
  5. Step 5: Solve for x
    x = 81,110.77/421.03
  6. Step 6: Final answer
    x = 192.65

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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.