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Finding the Fourth Proportional to 78.72, 117.84 and 51.60

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Solution

The fourth proportional to 78.72, 117.84 and 51.60 is: 77.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.72 : 117.84 = 51.60 : x
  2. Step 2: Convert to fraction form
    78.72/117.84 = 51.60/x
  3. Step 3: Cross multiply
    78.72x = 117.84 × 51.60
  4. Step 4: Simplify right side
    78.72x = 6,080.54
  5. Step 5: Solve for x
    x = 6,080.54/78.72
  6. Step 6: Final answer
    x = 77.24

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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.