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Finding the Fourth Proportional to 159.90, 239.90 and 78.75

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Solution

The fourth proportional to 159.90, 239.90 and 78.75 is: 118.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    159.90 : 239.90 = 78.75 : x
  2. Step 2: Convert to fraction form
    159.90/239.90 = 78.75/x
  3. Step 3: Cross multiply
    159.90x = 239.90 × 78.75
  4. Step 4: Simplify right side
    159.90x = 18,892.13
  5. Step 5: Solve for x
    x = 18,892.13/159.90
  6. Step 6: Final answer
    x = 118.15

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.