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Finding the Fourth Proportional to 93.42, 128.12 and 90.78

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Solution

The fourth proportional to 93.42, 128.12 and 90.78 is: 124.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.42 : 128.12 = 90.78 : x
  2. Step 2: Convert to fraction form
    93.42/128.12 = 90.78/x
  3. Step 3: Cross multiply
    93.42x = 128.12 × 90.78
  4. Step 4: Simplify right side
    93.42x = 11,630.73
  5. Step 5: Solve for x
    x = 11,630.73/93.42
  6. Step 6: Final answer
    x = 124.50

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.