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Finding the Fourth Proportional to 140.40, 209.88 and 128.16

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Solution

The fourth proportional to 140.40, 209.88 and 128.16 is: 191.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    140.40 : 209.88 = 128.16 : x
  2. Step 2: Convert to fraction form
    140.40/209.88 = 128.16/x
  3. Step 3: Cross multiply
    140.40x = 209.88 × 128.16
  4. Step 4: Simplify right side
    140.40x = 26,898.22
  5. Step 5: Solve for x
    x = 26,898.22/140.40
  6. Step 6: Final answer
    x = 191.58

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.