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Finding the Fourth Proportional to 115.31, 159.12 and 90.81

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Solution

The fourth proportional to 115.31, 159.12 and 90.81 is: 125.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.31 : 159.12 = 90.81 : x
  2. Step 2: Convert to fraction form
    115.31/159.12 = 90.81/x
  3. Step 3: Cross multiply
    115.31x = 159.12 × 90.81
  4. Step 4: Simplify right side
    115.31x = 14,449.69
  5. Step 5: Solve for x
    x = 14,449.69/115.31
  6. Step 6: Final answer
    x = 125.31

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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.