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Finding the Fourth Proportional to 78.15, 107.91 and 70.77

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Solution

The fourth proportional to 78.15, 107.91 and 70.77 is: 97.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.15 : 107.91 = 70.77 : x
  2. Step 2: Convert to fraction form
    78.15/107.91 = 70.77/x
  3. Step 3: Cross multiply
    78.15x = 107.91 × 70.77
  4. Step 4: Simplify right side
    78.15x = 7,636.79
  5. Step 5: Solve for x
    x = 7,636.79/78.15
  6. Step 6: Final answer
    x = 97.72

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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.