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Finding the Fourth Proportional to 90.65, 136.01 and 71.42

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Solution

The fourth proportional to 90.65, 136.01 and 71.42 is: 107.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.65 : 136.01 = 71.42 : x
  2. Step 2: Convert to fraction form
    90.65/136.01 = 71.42/x
  3. Step 3: Cross multiply
    90.65x = 136.01 × 71.42
  4. Step 4: Simplify right side
    90.65x = 9,713.33
  5. Step 5: Solve for x
    x = 9,713.33/90.65
  6. Step 6: Final answer
    x = 107.15

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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.