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Finding the Fourth Proportional to 136.80, 205 and 90.42

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Solution

The fourth proportional to 136.80, 205 and 90.42 is: 135.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.80 : 205 = 90.42 : x
  2. Step 2: Convert to fraction form
    136.80/205 = 90.42/x
  3. Step 3: Cross multiply
    136.80x = 205 × 90.42
  4. Step 4: Simplify right side
    136.80x = 18,536.10
  5. Step 5: Solve for x
    x = 18,536.10/136.80
  6. Step 6: Final answer
    x = 135.50

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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.