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Finding the Fourth Proportional to 78.42, 108.20 and 49.31

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Solution

The fourth proportional to 78.42, 108.20 and 49.31 is: 68.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 108.20 = 49.31 : x
  2. Step 2: Convert to fraction form
    78.42/108.20 = 49.31/x
  3. Step 3: Cross multiply
    78.42x = 108.20 × 49.31
  4. Step 4: Simplify right side
    78.42x = 5,334.55
  5. Step 5: Solve for x
    x = 5,334.55/78.42
  6. Step 6: Final answer
    x = 68.03

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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.