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Finding the Fourth Proportional to 91.10, 135.55 and 90.78

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Solution

The fourth proportional to 91.10, 135.55 and 90.78 is: 135.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.10 : 135.55 = 90.78 : x
  2. Step 2: Convert to fraction form
    91.10/135.55 = 90.78/x
  3. Step 3: Cross multiply
    91.10x = 135.55 × 90.78
  4. Step 4: Simplify right side
    91.10x = 12,305.23
  5. Step 5: Solve for x
    x = 12,305.23/91.10
  6. Step 6: Final answer
    x = 135.07

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.