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Finding the Fourth Proportional to 78.21, 107.93 and 74.57

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Solution

The fourth proportional to 78.21, 107.93 and 74.57 is: 102.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.21 : 107.93 = 74.57 : x
  2. Step 2: Convert to fraction form
    78.21/107.93 = 74.57/x
  3. Step 3: Cross multiply
    78.21x = 107.93 × 74.57
  4. Step 4: Simplify right side
    78.21x = 8,047.99
  5. Step 5: Solve for x
    x = 8,047.99/78.21
  6. Step 6: Final answer
    x = 102.90

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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.