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Finding the Fourth Proportional to 115.80, 159.68 and 86.40

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Solution

The fourth proportional to 115.80, 159.68 and 86.40 is: 119.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.80 : 159.68 = 86.40 : x
  2. Step 2: Convert to fraction form
    115.80/159.68 = 86.40/x
  3. Step 3: Cross multiply
    115.80x = 159.68 × 86.40
  4. Step 4: Simplify right side
    115.80x = 13,796.35
  5. Step 5: Solve for x
    x = 13,796.35/115.80
  6. Step 6: Final answer
    x = 119.14

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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.