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Finding the Fourth Proportional to 428.99, 643.28 and 185.72

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Solution

The fourth proportional to 428.99, 643.28 and 185.72 is: 278.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.99 : 643.28 = 185.72 : x
  2. Step 2: Convert to fraction form
    428.99/643.28 = 185.72/x
  3. Step 3: Cross multiply
    428.99x = 643.28 × 185.72
  4. Step 4: Simplify right side
    428.99x = 119,465.82
  5. Step 5: Solve for x
    x = 119,465.82/428.99
  6. Step 6: Final answer
    x = 278.48

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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.