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Finding the Fourth Proportional to 78.84, 118.40 and 69.72

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Solution

The fourth proportional to 78.84, 118.40 and 69.72 is: 104.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.84 : 118.40 = 69.72 : x
  2. Step 2: Convert to fraction form
    78.84/118.40 = 69.72/x
  3. Step 3: Cross multiply
    78.84x = 118.40 × 69.72
  4. Step 4: Simplify right side
    78.84x = 8,254.85
  5. Step 5: Solve for x
    x = 8,254.85/78.84
  6. Step 6: Final answer
    x = 104.70

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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.