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Finding the Fourth Proportional to 93, 138.68 and 86.40

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Solution

The fourth proportional to 93, 138.68 and 86.40 is: 128.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    93 : 138.68 = 86.40 : x
  2. Step 2: Convert to fraction form
    93/138.68 = 86.40/x
  3. Step 3: Cross multiply
    93x = 138.68 × 86.40
  4. Step 4: Simplify right side
    93x = 11,981.95
  5. Step 5: Solve for x
    x = 11,981.95/93
  6. Step 6: Final answer
    x = 128.84

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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.