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Finding the Fourth Proportional to 128.48, 177.36 and 84.20

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Solution

The fourth proportional to 128.48, 177.36 and 84.20 is: 116.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.48 : 177.36 = 84.20 : x
  2. Step 2: Convert to fraction form
    128.48/177.36 = 84.20/x
  3. Step 3: Cross multiply
    128.48x = 177.36 × 84.20
  4. Step 4: Simplify right side
    128.48x = 14,933.71
  5. Step 5: Solve for x
    x = 14,933.71/128.48
  6. Step 6: Final answer
    x = 116.23

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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.