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Finding the Fourth Proportional to 142.85, 214.38 and 77.90

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Solution

The fourth proportional to 142.85, 214.38 and 77.90 is: 116.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.85 : 214.38 = 77.90 : x
  2. Step 2: Convert to fraction form
    142.85/214.38 = 77.90/x
  3. Step 3: Cross multiply
    142.85x = 214.38 × 77.90
  4. Step 4: Simplify right side
    142.85x = 16,699.13
  5. Step 5: Solve for x
    x = 16,699.13/142.85
  6. Step 6: Final answer
    x = 116.90

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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.