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Finding the Fourth Proportional to 492.15, 678.72 and 398.34

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Solution

The fourth proportional to 492.15, 678.72 and 398.34 is: 549.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    492.15 : 678.72 = 398.34 : x
  2. Step 2: Convert to fraction form
    492.15/678.72 = 398.34/x
  3. Step 3: Cross multiply
    492.15x = 678.72 × 398.34
  4. Step 4: Simplify right side
    492.15x = 270,361.32
  5. Step 5: Solve for x
    x = 270,361.32/492.15
  6. Step 6: Final answer
    x = 549.35

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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.