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Finding the Fourth Proportional to 78.90, 109.02 and 76.50

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Solution

The fourth proportional to 78.90, 109.02 and 76.50 is: 105.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.90 : 109.02 = 76.50 : x
  2. Step 2: Convert to fraction form
    78.90/109.02 = 76.50/x
  3. Step 3: Cross multiply
    78.90x = 109.02 × 76.50
  4. Step 4: Simplify right side
    78.90x = 8,340.03
  5. Step 5: Solve for x
    x = 8,340.03/78.90
  6. Step 6: Final answer
    x = 105.70

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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.