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Finding the Fourth Proportional to 128.95, 177.78 and 111.40

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Solution

The fourth proportional to 128.95, 177.78 and 111.40 is: 153.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.95 : 177.78 = 111.40 : x
  2. Step 2: Convert to fraction form
    128.95/177.78 = 111.40/x
  3. Step 3: Cross multiply
    128.95x = 177.78 × 111.40
  4. Step 4: Simplify right side
    128.95x = 19,804.69
  5. Step 5: Solve for x
    x = 19,804.69/128.95
  6. Step 6: Final answer
    x = 153.58

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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.