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Finding the Fourth Proportional to 79.38, 117.72 and 78.30

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Solution

The fourth proportional to 79.38, 117.72 and 78.30 is: 116.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.38 : 117.72 = 78.30 : x
  2. Step 2: Convert to fraction form
    79.38/117.72 = 78.30/x
  3. Step 3: Cross multiply
    79.38x = 117.72 × 78.30
  4. Step 4: Simplify right side
    79.38x = 9,217.48
  5. Step 5: Solve for x
    x = 9,217.48/79.38
  6. Step 6: Final answer
    x = 116.12

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Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.