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Finding the Fourth Proportional to 128.79, 178.00 and 113.60

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Solution

The fourth proportional to 128.79, 178.00 and 113.60 is: 157.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.79 : 178.00 = 113.60 : x
  2. Step 2: Convert to fraction form
    128.79/178.00 = 113.60/x
  3. Step 3: Cross multiply
    128.79x = 178.00 × 113.60
  4. Step 4: Simplify right side
    128.79x = 20,220.96
  5. Step 5: Solve for x
    x = 20,220.96/128.79
  6. Step 6: Final answer
    x = 157.01

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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.