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Finding the Fourth Proportional to 128.60, 192.90 and 124.20

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Solution

The fourth proportional to 128.60, 192.90 and 124.20 is: 186.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.60 : 192.90 = 124.20 : x
  2. Step 2: Convert to fraction form
    128.60/192.90 = 124.20/x
  3. Step 3: Cross multiply
    128.60x = 192.90 × 124.20
  4. Step 4: Simplify right side
    128.60x = 23,958.18
  5. Step 5: Solve for x
    x = 23,958.18/128.60
  6. Step 6: Final answer
    x = 186.30

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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.