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Finding the Fourth Proportional to 90.80, 126 and 86.88

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Solution

The fourth proportional to 90.80, 126 and 86.88 is: 120.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.80 : 126 = 86.88 : x
  2. Step 2: Convert to fraction form
    90.80/126 = 86.88/x
  3. Step 3: Cross multiply
    90.80x = 126 × 86.88
  4. Step 4: Simplify right side
    90.80x = 10,946.88
  5. Step 5: Solve for x
    x = 10,946.88/90.80
  6. Step 6: Final answer
    x = 120.56

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.