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Finding the Fourth Proportional to 138.93, 207.30 and 128.16

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Solution

The fourth proportional to 138.93, 207.30 and 128.16 is: 191.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.93 : 207.30 = 128.16 : x
  2. Step 2: Convert to fraction form
    138.93/207.30 = 128.16/x
  3. Step 3: Cross multiply
    138.93x = 207.30 × 128.16
  4. Step 4: Simplify right side
    138.93x = 26,567.57
  5. Step 5: Solve for x
    x = 26,567.57/138.93
  6. Step 6: Final answer
    x = 191.23

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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.