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Finding the Fourth Proportional to 93.78, 129.42 and 77.40

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Solution

The fourth proportional to 93.78, 129.42 and 77.40 is: 106.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.78 : 129.42 = 77.40 : x
  2. Step 2: Convert to fraction form
    93.78/129.42 = 77.40/x
  3. Step 3: Cross multiply
    93.78x = 129.42 × 77.40
  4. Step 4: Simplify right side
    93.78x = 10,017.11
  5. Step 5: Solve for x
    x = 10,017.11/93.78
  6. Step 6: Final answer
    x = 106.81

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.