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Finding the Fourth Proportional to 103.90, 155.40 and 87.70

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Solution

The fourth proportional to 103.90, 155.40 and 87.70 is: 131.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.90 : 155.40 = 87.70 : x
  2. Step 2: Convert to fraction form
    103.90/155.40 = 87.70/x
  3. Step 3: Cross multiply
    103.90x = 155.40 × 87.70
  4. Step 4: Simplify right side
    103.90x = 13,628.58
  5. Step 5: Solve for x
    x = 13,628.58/103.90
  6. Step 6: Final answer
    x = 131.17

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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.