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Finding the Fourth Proportional to 78.45, 117.75 and 76.77

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Solution

The fourth proportional to 78.45, 117.75 and 76.77 is: 115.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.45 : 117.75 = 76.77 : x
  2. Step 2: Convert to fraction form
    78.45/117.75 = 76.77/x
  3. Step 3: Cross multiply
    78.45x = 117.75 × 76.77
  4. Step 4: Simplify right side
    78.45x = 9,039.67
  5. Step 5: Solve for x
    x = 9,039.67/78.45
  6. Step 6: Final answer
    x = 115.23

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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.