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Finding the Fourth Proportional to 90.86, 124.61 and 87.80

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Solution

The fourth proportional to 90.86, 124.61 and 87.80 is: 120.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.86 : 124.61 = 87.80 : x
  2. Step 2: Convert to fraction form
    90.86/124.61 = 87.80/x
  3. Step 3: Cross multiply
    90.86x = 124.61 × 87.80
  4. Step 4: Simplify right side
    90.86x = 10,939.70
  5. Step 5: Solve for x
    x = 10,939.70/90.86
  6. Step 6: Final answer
    x = 120.41

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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.