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Finding the Fourth Proportional to 77.76, 107.52 and 64.80

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Solution

The fourth proportional to 77.76, 107.52 and 64.80 is: 89.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.76 : 107.52 = 64.80 : x
  2. Step 2: Convert to fraction form
    77.76/107.52 = 64.80/x
  3. Step 3: Cross multiply
    77.76x = 107.52 × 64.80
  4. Step 4: Simplify right side
    77.76x = 6,967.30
  5. Step 5: Solve for x
    x = 6,967.30/77.76
  6. Step 6: Final answer
    x = 89.60

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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.