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Finding the Fourth Proportional to 90.90, 124.79 and 78.60

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Solution

The fourth proportional to 90.90, 124.79 and 78.60 is: 107.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.90 : 124.79 = 78.60 : x
  2. Step 2: Convert to fraction form
    90.90/124.79 = 78.60/x
  3. Step 3: Cross multiply
    90.90x = 124.79 × 78.60
  4. Step 4: Simplify right side
    90.90x = 9,808.49
  5. Step 5: Solve for x
    x = 9,808.49/90.90
  6. Step 6: Final answer
    x = 107.90

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.