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Finding the Fourth Proportional to 207.12, 285.74 and 128.40

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Solution

The fourth proportional to 207.12, 285.74 and 128.40 is: 177.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.12 : 285.74 = 128.40 : x
  2. Step 2: Convert to fraction form
    207.12/285.74 = 128.40/x
  3. Step 3: Cross multiply
    207.12x = 285.74 × 128.40
  4. Step 4: Simplify right side
    207.12x = 36,689.02
  5. Step 5: Solve for x
    x = 36,689.02/207.12
  6. Step 6: Final answer
    x = 177.14

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.