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Finding the Fourth Proportional to 421.08, 631.64 and 128.60

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Solution

The fourth proportional to 421.08, 631.64 and 128.60 is: 192.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.08 : 631.64 = 128.60 : x
  2. Step 2: Convert to fraction form
    421.08/631.64 = 128.60/x
  3. Step 3: Cross multiply
    421.08x = 631.64 × 128.60
  4. Step 4: Simplify right side
    421.08x = 81,228.44
  5. Step 5: Solve for x
    x = 81,228.44/421.08
  6. Step 6: Final answer
    x = 192.91

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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.