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Finding the Fourth Proportional to 102.78, 154.20 and 90.60

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Solution

The fourth proportional to 102.78, 154.20 and 90.60 is: 135.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.78 : 154.20 = 90.60 : x
  2. Step 2: Convert to fraction form
    102.78/154.20 = 90.60/x
  3. Step 3: Cross multiply
    102.78x = 154.20 × 90.60
  4. Step 4: Simplify right side
    102.78x = 13,970.52
  5. Step 5: Solve for x
    x = 13,970.52/102.78
  6. Step 6: Final answer
    x = 135.93

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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.