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Finding the Fourth Proportional to 78.22, 117.70 and 64.61

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Solution

The fourth proportional to 78.22, 117.70 and 64.61 is: 97.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.22 : 117.70 = 64.61 : x
  2. Step 2: Convert to fraction form
    78.22/117.70 = 64.61/x
  3. Step 3: Cross multiply
    78.22x = 117.70 × 64.61
  4. Step 4: Simplify right side
    78.22x = 7,603.85
  5. Step 5: Solve for x
    x = 7,603.85/78.22
  6. Step 6: Final answer
    x = 97.21

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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.