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Finding the Fourth Proportional to 103.78, 142.90 and 89.00

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Solution

The fourth proportional to 103.78, 142.90 and 89.00 is: 122.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.78 : 142.90 = 89.00 : x
  2. Step 2: Convert to fraction form
    103.78/142.90 = 89.00/x
  3. Step 3: Cross multiply
    103.78x = 142.90 × 89.00
  4. Step 4: Simplify right side
    103.78x = 12,717.70
  5. Step 5: Solve for x
    x = 12,717.70/103.78
  6. Step 6: Final answer
    x = 122.54

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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.