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Finding the Fourth Proportional to 78.81, 118.14 and 56.79

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Solution

The fourth proportional to 78.81, 118.14 and 56.79 is: 85.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.81 : 118.14 = 56.79 : x
  2. Step 2: Convert to fraction form
    78.81/118.14 = 56.79/x
  3. Step 3: Cross multiply
    78.81x = 118.14 × 56.79
  4. Step 4: Simplify right side
    78.81x = 6,709.17
  5. Step 5: Solve for x
    x = 6,709.17/78.81
  6. Step 6: Final answer
    x = 85.13

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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.