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Finding the Fourth Proportional to 105.78, 158.80 and 90.66

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Solution

The fourth proportional to 105.78, 158.80 and 90.66 is: 136.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.78 : 158.80 = 90.66 : x
  2. Step 2: Convert to fraction form
    105.78/158.80 = 90.66/x
  3. Step 3: Cross multiply
    105.78x = 158.80 × 90.66
  4. Step 4: Simplify right side
    105.78x = 14,396.81
  5. Step 5: Solve for x
    x = 14,396.81/105.78
  6. Step 6: Final answer
    x = 136.10

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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.