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Finding the Fourth Proportional to 128.60, 192.90 and 113.40

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Solution

The fourth proportional to 128.60, 192.90 and 113.40 is: 170.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.60 : 192.90 = 113.40 : x
  2. Step 2: Convert to fraction form
    128.60/192.90 = 113.40/x
  3. Step 3: Cross multiply
    128.60x = 192.90 × 113.40
  4. Step 4: Simplify right side
    128.60x = 21,874.86
  5. Step 5: Solve for x
    x = 21,874.86/128.60
  6. Step 6: Final answer
    x = 170.10

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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.