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Finding the Fourth Proportional to 287.12, 430.68 and 81.70

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Solution

The fourth proportional to 287.12, 430.68 and 81.70 is: 122.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.12 : 430.68 = 81.70 : x
  2. Step 2: Convert to fraction form
    287.12/430.68 = 81.70/x
  3. Step 3: Cross multiply
    287.12x = 430.68 × 81.70
  4. Step 4: Simplify right side
    287.12x = 35,186.56
  5. Step 5: Solve for x
    x = 35,186.56/287.12
  6. Step 6: Final answer
    x = 122.55

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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.