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Finding the Fourth Proportional to 147.20, 220.61 and 78.75

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Solution

The fourth proportional to 147.20, 220.61 and 78.75 is: 118.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    147.20 : 220.61 = 78.75 : x
  2. Step 2: Convert to fraction form
    147.20/220.61 = 78.75/x
  3. Step 3: Cross multiply
    147.20x = 220.61 × 78.75
  4. Step 4: Simplify right side
    147.20x = 17,373.04
  5. Step 5: Solve for x
    x = 17,373.04/147.20
  6. Step 6: Final answer
    x = 118.02

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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.