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Finding the Fourth Proportional to 93.40, 128.78 and 77.88

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Solution

The fourth proportional to 93.40, 128.78 and 77.88 is: 107.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.40 : 128.78 = 77.88 : x
  2. Step 2: Convert to fraction form
    93.40/128.78 = 77.88/x
  3. Step 3: Cross multiply
    93.40x = 128.78 × 77.88
  4. Step 4: Simplify right side
    93.40x = 10,029.39
  5. Step 5: Solve for x
    x = 10,029.39/93.40
  6. Step 6: Final answer
    x = 107.38

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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.