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Finding the Fourth Proportional to 147.21, 220.75 and 78.72

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Solution

The fourth proportional to 147.21, 220.75 and 78.72 is: 118.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    147.21 : 220.75 = 78.72 : x
  2. Step 2: Convert to fraction form
    147.21/220.75 = 78.72/x
  3. Step 3: Cross multiply
    147.21x = 220.75 × 78.72
  4. Step 4: Simplify right side
    147.21x = 17,377.44
  5. Step 5: Solve for x
    x = 17,377.44/147.21
  6. Step 6: Final answer
    x = 118.05

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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.