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Finding the Fourth Proportional to 207.15, 310.72 and 85.42

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Solution

The fourth proportional to 207.15, 310.72 and 85.42 is: 128.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.15 : 310.72 = 85.42 : x
  2. Step 2: Convert to fraction form
    207.15/310.72 = 85.42/x
  3. Step 3: Cross multiply
    207.15x = 310.72 × 85.42
  4. Step 4: Simplify right side
    207.15x = 26,541.49
  5. Step 5: Solve for x
    x = 26,541.49/207.15
  6. Step 6: Final answer
    x = 128.13

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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.