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Finding the Fourth Proportional to 78.21, 117.07 and 65.95

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Solution

The fourth proportional to 78.21, 117.07 and 65.95 is: 98.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.21 : 117.07 = 65.95 : x
  2. Step 2: Convert to fraction form
    78.21/117.07 = 65.95/x
  3. Step 3: Cross multiply
    78.21x = 117.07 × 65.95
  4. Step 4: Simplify right side
    78.21x = 7,720.31
  5. Step 5: Solve for x
    x = 7,720.31/78.21
  6. Step 6: Final answer
    x = 98.71

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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.