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Finding the Fourth Proportional to 128.88, 177.76 and 79.76

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Solution

The fourth proportional to 128.88, 177.76 and 79.76 is: 110.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.88 : 177.76 = 79.76 : x
  2. Step 2: Convert to fraction form
    128.88/177.76 = 79.76/x
  3. Step 3: Cross multiply
    128.88x = 177.76 × 79.76
  4. Step 4: Simplify right side
    128.88x = 14,178.14
  5. Step 5: Solve for x
    x = 14,178.14/128.88
  6. Step 6: Final answer
    x = 110.01

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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.