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Finding the Fourth Proportional to 102.76, 154.20 and 78.64

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Solution

The fourth proportional to 102.76, 154.20 and 78.64 is: 118.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.76 : 154.20 = 78.64 : x
  2. Step 2: Convert to fraction form
    102.76/154.20 = 78.64/x
  3. Step 3: Cross multiply
    102.76x = 154.20 × 78.64
  4. Step 4: Simplify right side
    102.76x = 12,126.29
  5. Step 5: Solve for x
    x = 12,126.29/102.76
  6. Step 6: Final answer
    x = 118.01

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.