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Finding the Fourth Proportional to 405.89, 608.85 and 128.30

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Solution

The fourth proportional to 405.89, 608.85 and 128.30 is: 192.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.89 : 608.85 = 128.30 : x
  2. Step 2: Convert to fraction form
    405.89/608.85 = 128.30/x
  3. Step 3: Cross multiply
    405.89x = 608.85 × 128.30
  4. Step 4: Simplify right side
    405.89x = 78,113.81
  5. Step 5: Solve for x
    x = 78,113.81/405.89
  6. Step 6: Final answer
    x = 192.45

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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.