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Finding the Fourth Proportional to 93.71, 128.78 and 87.64

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Solution

The fourth proportional to 93.71, 128.78 and 87.64 is: 120.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.71 : 128.78 = 87.64 : x
  2. Step 2: Convert to fraction form
    93.71/128.78 = 87.64/x
  3. Step 3: Cross multiply
    93.71x = 128.78 × 87.64
  4. Step 4: Simplify right side
    93.71x = 11,286.28
  5. Step 5: Solve for x
    x = 11,286.28/93.71
  6. Step 6: Final answer
    x = 120.44

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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.