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Finding the Fourth Proportional to 99.90, 138.04 and 84.38

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Solution

The fourth proportional to 99.90, 138.04 and 84.38 is: 116.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.90 : 138.04 = 84.38 : x
  2. Step 2: Convert to fraction form
    99.90/138.04 = 84.38/x
  3. Step 3: Cross multiply
    99.90x = 138.04 × 84.38
  4. Step 4: Simplify right side
    99.90x = 11,646.91
  5. Step 5: Solve for x
    x = 11,646.91/99.90
  6. Step 6: Final answer
    x = 116.59

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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.