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Finding the Fourth Proportional to 136.76, 188.78 and 90.20

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Solution

The fourth proportional to 136.76, 188.78 and 90.20 is: 124.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.76 : 188.78 = 90.20 : x
  2. Step 2: Convert to fraction form
    136.76/188.78 = 90.20/x
  3. Step 3: Cross multiply
    136.76x = 188.78 × 90.20
  4. Step 4: Simplify right side
    136.76x = 17,026.56
  5. Step 5: Solve for x
    x = 17,026.56/136.76
  6. Step 6: Final answer
    x = 124.50

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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.