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Finding the Fourth Proportional to 78.43, 117.51 and 47.90

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Solution

The fourth proportional to 78.43, 117.51 and 47.90 is: 71.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.43 : 117.51 = 47.90 : x
  2. Step 2: Convert to fraction form
    78.43/117.51 = 47.90/x
  3. Step 3: Cross multiply
    78.43x = 117.51 × 47.90
  4. Step 4: Simplify right side
    78.43x = 5,628.85
  5. Step 5: Solve for x
    x = 5,628.85/78.43
  6. Step 6: Final answer
    x = 71.77

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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.