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Finding the Fourth Proportional to 128.40, 177.09 and 79.23

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Solution

The fourth proportional to 128.40, 177.09 and 79.23 is: 109.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.40 : 177.09 = 79.23 : x
  2. Step 2: Convert to fraction form
    128.40/177.09 = 79.23/x
  3. Step 3: Cross multiply
    128.40x = 177.09 × 79.23
  4. Step 4: Simplify right side
    128.40x = 14,030.84
  5. Step 5: Solve for x
    x = 14,030.84/128.40
  6. Step 6: Final answer
    x = 109.27

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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.