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Finding the Fourth Proportional to 102.12, 140.81 and 64.70

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Solution

The fourth proportional to 102.12, 140.81 and 64.70 is: 89.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.12 : 140.81 = 64.70 : x
  2. Step 2: Convert to fraction form
    102.12/140.81 = 64.70/x
  3. Step 3: Cross multiply
    102.12x = 140.81 × 64.70
  4. Step 4: Simplify right side
    102.12x = 9,109.89
  5. Step 5: Solve for x
    x = 9,109.89/102.12
  6. Step 6: Final answer
    x = 89.21

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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.