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Finding the Fourth Proportional to 90, 124.21 and 55.50

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Solution

The fourth proportional to 90, 124.21 and 55.50 is: 76.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 124.21 = 55.50 : x
  2. Step 2: Convert to fraction form
    90/124.21 = 55.50/x
  3. Step 3: Cross multiply
    90x = 124.21 × 55.50
  4. Step 4: Simplify right side
    90x = 6,893.66
  5. Step 5: Solve for x
    x = 6,893.66/90
  6. Step 6: Final answer
    x = 76.60

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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.