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Finding the Fourth Proportional to 78.77, 108.46 and 69.90

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Solution

The fourth proportional to 78.77, 108.46 and 69.90 is: 96.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.77 : 108.46 = 69.90 : x
  2. Step 2: Convert to fraction form
    78.77/108.46 = 69.90/x
  3. Step 3: Cross multiply
    78.77x = 108.46 × 69.90
  4. Step 4: Simplify right side
    78.77x = 7,581.35
  5. Step 5: Solve for x
    x = 7,581.35/78.77
  6. Step 6: Final answer
    x = 96.25

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.