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Finding the Fourth Proportional to 78.32, 116.64 and 76.80

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Solution

The fourth proportional to 78.32, 116.64 and 76.80 is: 114.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.32 : 116.64 = 76.80 : x
  2. Step 2: Convert to fraction form
    78.32/116.64 = 76.80/x
  3. Step 3: Cross multiply
    78.32x = 116.64 × 76.80
  4. Step 4: Simplify right side
    78.32x = 8,957.95
  5. Step 5: Solve for x
    x = 8,957.95/78.32
  6. Step 6: Final answer
    x = 114.38

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.