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Finding the Fourth Proportional to 100.38, 138.51 and 71.31

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Solution

The fourth proportional to 100.38, 138.51 and 71.31 is: 98.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.38 : 138.51 = 71.31 : x
  2. Step 2: Convert to fraction form
    100.38/138.51 = 71.31/x
  3. Step 3: Cross multiply
    100.38x = 138.51 × 71.31
  4. Step 4: Simplify right side
    100.38x = 9,877.15
  5. Step 5: Solve for x
    x = 9,877.15/100.38
  6. Step 6: Final answer
    x = 98.40

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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.