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Finding the Fourth Proportional to 428.84, 643.30 and 120.70

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Solution

The fourth proportional to 428.84, 643.30 and 120.70 is: 181.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.84 : 643.30 = 120.70 : x
  2. Step 2: Convert to fraction form
    428.84/643.30 = 120.70/x
  3. Step 3: Cross multiply
    428.84x = 643.30 × 120.70
  4. Step 4: Simplify right side
    428.84x = 77,643.09
  5. Step 5: Solve for x
    x = 77,643.09/428.84
  6. Step 6: Final answer
    x = 181.05

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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.