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Finding the Fourth Proportional to 103.90, 156.05 and 91.98

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Solution

The fourth proportional to 103.90, 156.05 and 91.98 is: 138.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.90 : 156.05 = 91.98 : x
  2. Step 2: Convert to fraction form
    103.90/156.05 = 91.98/x
  3. Step 3: Cross multiply
    103.90x = 156.05 × 91.98
  4. Step 4: Simplify right side
    103.90x = 14,353.48
  5. Step 5: Solve for x
    x = 14,353.48/103.90
  6. Step 6: Final answer
    x = 138.15

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.