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Finding the Fourth Proportional to 128.58, 192.80 and 74.51

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Solution

The fourth proportional to 128.58, 192.80 and 74.51 is: 111.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.58 : 192.80 = 74.51 : x
  2. Step 2: Convert to fraction form
    128.58/192.80 = 74.51/x
  3. Step 3: Cross multiply
    128.58x = 192.80 × 74.51
  4. Step 4: Simplify right side
    128.58x = 14,365.53
  5. Step 5: Solve for x
    x = 14,365.53/128.58
  6. Step 6: Final answer
    x = 111.72

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.