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Finding the Fourth Proportional to 142.80, 214.20 and 78.66

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Solution

The fourth proportional to 142.80, 214.20 and 78.66 is: 117.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.80 : 214.20 = 78.66 : x
  2. Step 2: Convert to fraction form
    142.80/214.20 = 78.66/x
  3. Step 3: Cross multiply
    142.80x = 214.20 × 78.66
  4. Step 4: Simplify right side
    142.80x = 16,848.97
  5. Step 5: Solve for x
    x = 16,848.97/142.80
  6. Step 6: Final answer
    x = 117.99

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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.