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Finding the Fourth Proportional to 100.39, 138.36 and 89.47

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Solution

The fourth proportional to 100.39, 138.36 and 89.47 is: 123.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.39 : 138.36 = 89.47 : x
  2. Step 2: Convert to fraction form
    100.39/138.36 = 89.47/x
  3. Step 3: Cross multiply
    100.39x = 138.36 × 89.47
  4. Step 4: Simplify right side
    100.39x = 12,379.07
  5. Step 5: Solve for x
    x = 12,379.07/100.39
  6. Step 6: Final answer
    x = 123.31

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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.