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Finding the Fourth Proportional to 78.28, 117.12 and 71.80

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Solution

The fourth proportional to 78.28, 117.12 and 71.80 is: 107.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.28 : 117.12 = 71.80 : x
  2. Step 2: Convert to fraction form
    78.28/117.12 = 71.80/x
  3. Step 3: Cross multiply
    78.28x = 117.12 × 71.80
  4. Step 4: Simplify right side
    78.28x = 8,409.22
  5. Step 5: Solve for x
    x = 8,409.22/78.28
  6. Step 6: Final answer
    x = 107.42

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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.