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Finding the Fourth Proportional to 91.80, 126.54 and 87.12

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Solution

The fourth proportional to 91.80, 126.54 and 87.12 is: 120.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.80 : 126.54 = 87.12 : x
  2. Step 2: Convert to fraction form
    91.80/126.54 = 87.12/x
  3. Step 3: Cross multiply
    91.80x = 126.54 × 87.12
  4. Step 4: Simplify right side
    91.80x = 11,024.16
  5. Step 5: Solve for x
    x = 11,024.16/91.80
  6. Step 6: Final answer
    x = 120.09

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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.