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Finding the Fourth Proportional to 99.95, 138.02 and 85.31

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Solution

The fourth proportional to 99.95, 138.02 and 85.31 is: 117.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.95 : 138.02 = 85.31 : x
  2. Step 2: Convert to fraction form
    99.95/138.02 = 85.31/x
  3. Step 3: Cross multiply
    99.95x = 138.02 × 85.31
  4. Step 4: Simplify right side
    99.95x = 11,774.01
  5. Step 5: Solve for x
    x = 11,774.01/99.95
  6. Step 6: Final answer
    x = 117.80

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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.