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Finding the Fourth Proportional to 78.66, 117.19 and 77.90

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Solution

The fourth proportional to 78.66, 117.19 and 77.90 is: 116.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.66 : 117.19 = 77.90 : x
  2. Step 2: Convert to fraction form
    78.66/117.19 = 77.90/x
  3. Step 3: Cross multiply
    78.66x = 117.19 × 77.90
  4. Step 4: Simplify right side
    78.66x = 9,129.10
  5. Step 5: Solve for x
    x = 9,129.10/78.66
  6. Step 6: Final answer
    x = 116.06

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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.