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Finding the Fourth Proportional to 78.15, 116.61 and 77.70

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Solution

The fourth proportional to 78.15, 116.61 and 77.70 is: 115.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.15 : 116.61 = 77.70 : x
  2. Step 2: Convert to fraction form
    78.15/116.61 = 77.70/x
  3. Step 3: Cross multiply
    78.15x = 116.61 × 77.70
  4. Step 4: Simplify right side
    78.15x = 9,060.60
  5. Step 5: Solve for x
    x = 9,060.60/78.15
  6. Step 6: Final answer
    x = 115.94

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.