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Finding the Fourth Proportional to 492.12, 678.90 and 285

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Solution

The fourth proportional to 492.12, 678.90 and 285 is: 393.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    492.12 : 678.90 = 285 : x
  2. Step 2: Convert to fraction form
    492.12/678.90 = 285/x
  3. Step 3: Cross multiply
    492.12x = 678.90 × 285
  4. Step 4: Simplify right side
    492.12x = 193,486.50
  5. Step 5: Solve for x
    x = 193,486.50/492.12
  6. Step 6: Final answer
    x = 393.17

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.