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Finding the Fourth Proportional to 78.46, 108.21 and 61

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Solution

The fourth proportional to 78.46, 108.21 and 61 is: 84.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.46 : 108.21 = 61 : x
  2. Step 2: Convert to fraction form
    78.46/108.21 = 61/x
  3. Step 3: Cross multiply
    78.46x = 108.21 × 61
  4. Step 4: Simplify right side
    78.46x = 6,600.81
  5. Step 5: Solve for x
    x = 6,600.81/78.46
  6. Step 6: Final answer
    x = 84.13

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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.