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Finding the Fourth Proportional to 428.85, 643.32 and 185.40

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Solution

The fourth proportional to 428.85, 643.32 and 185.40 is: 278.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.85 : 643.32 = 185.40 : x
  2. Step 2: Convert to fraction form
    428.85/643.32 = 185.40/x
  3. Step 3: Cross multiply
    428.85x = 643.32 × 185.40
  4. Step 4: Simplify right side
    428.85x = 119,271.53
  5. Step 5: Solve for x
    x = 119,271.53/428.85
  6. Step 6: Final answer
    x = 278.12

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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.